I am using win 7. I have been using VMware for a while, I have installed ubuntu in it.  Now is there any way, I can use this ubuntu image (vmdk) to install another OS on my pc parallel to win7  I hope the question is clear.

Kind-of like  but slightly different (I think), in that I have 6 identical Acer Aspire Revo R3610 machines. One is (almost) configured to my requirements - when I'm done preparing it I'd like to make the other 5 machines absolutely the same. I'm very new to Ubuntu, what's the most straightforward (easiest) way of doing this?  The machines are going to live on different networks if that might otherwise be a problem (eg with Windows you can clone disks but you then have to make registry changes afterwards if they're going to run on the same network etc). The hardware in all 6 machines is, I stress, the same!  How can I efficiently clone one source image on to these identical machines?  Please restrict one software/solution per answer


I want to know how to move the camera along my view, so I can render the point where I want. I have seen many people moving the camera along their view and they are in modelling tab. I don't know whether there's an option to move.

I'm currently a beginner when it comes to 3D modelling but doing okay so far. I'm struggling a bit when it comes to the final renders of my scene, specifically on the camera view I want. Sometimes its to zoomed in and sometimes to zoomed out that it's gone out of the environment of the blender. I realized the settings for the camera on blender are for actual cameras / photography and I'm no expert on that too. A tip on how to control them precisely would be nice. Thank you.


A few days ago, I accidentally replaced my desktop in Mint 18 with a virtual console with an errant keystroke.  Not having an obvious way to reverse the changes, I logged in and typed exit to exit the console and go back to the desktop.  Instead, the computer rebooted, and I lost God-only-knows-how-much unsaved work.   After showing the Mint logo and flashing a message underneath it far too quickly to read, the computer now boots only to a black screen.  By pressing esc during reboot, I can get to a Startup Menu.  I ran disk checks and memory checks using it, and they all came up clean.  None of the other options in this menu help.  I have no idea what to do.  The screen is clearly receiving power, and the black screen that it boots to shows a dash or underscore in the top right corner.  How do I get my computer back?  It's an HP Pavilion laptop.


I received a rejection for my UK visa application. The letter in part says:  You have stated that you are employed by Al Majal Alarabi Group as an Electrical Engineer and that your total monthly income is  SAR (  as at 26/10/2020). I note that you have provided bank statement showing salary payments, however this bank statement shows number of additional cash deposits made to the account in the last few months. The origin of these funds have not been demonstrated and I note that you have declared that you do not have any additional income or savings. As such I am not satisfied that the statements made in your application form reflect your current personal circumstances regarding your employment, occupation or income  Can any body advise me how i can justify this one cash deposit. and what procedure i have to follow???

I read somewhere that 'funds parking' in your bank account during last minute is considered as  'mild deception' by consular officers which may lead to a denial.  Please explain why 'funds parking' in your bank account is considered a mild deception?. I see no reason why there is something wrong with this. People are free to do whatever they want with their bank account (e.g could even borrow funds from family) for travel.  I believe visa officers are always looking for several reasons to just deny you a visa.


Recently I have started reviewing mathematical notions, that I have always just accepted. Today it is one of the fundamental ones used in equations:      If we have an equation, then the equation holds if we do the same to both sides.    This seems perfectly obvious, but it must be stated as an axiom somewhere, presumably in formal logic(?). Only, I don't know what it would be called, or indeed how to search for it - does anybody knw?

It seems that given a statement $a = b$, that $a + c = b + c$ is assumed also to be true.  Why isn't this an axiom of arithmetic, like the commutative law or associative law?  Or is it a consequence of some other axiom of arithmetic?  Thanks!  Edit: I understand the intuitive meaning of equality. Answers that stated that $a = b$ means they are the same number or object make sense but what I'm asking is if there is an explicit law of replacement that allows us to make this intuitive truth a valid mathematical deduction. For example is there an axiom of Peano's Axioms or some other axiomatic system that allows for adding or multiplying both sides of an equation by the same number?   In all the texts I've come across I've never seen an axiom that states if $a = b$ then $a + c = b + c$. I have however seen if $a < b$ then $a + c < b + c$. In my view $<$ and $=$ are similar so the absence of a definition for equality is strange.


I found a short problem while reviewing some material.  True/False: The splitting field over $\mathbb Q$ of the polynomial $x^{17} − 5 \in  \mathbb Q[x]$ has a cyclic Galois group.  It's clear that this splitting field is a Galois extension, but I'm not sure how to solve the problem. Any help would be great.

I have some problems with this exercise. I don't know if it can be done. Consider the polynomial $ x^n - a \in \mathbb{Q} $ Can I compute the Galois group of this over $\mathbb{Q}$? Maybe having a nice "basis.  The splitting field is given by $\mathbb{Q}(\zeta_n,\alpha)$ , where $\zeta_n$ is a primitive root of unity , and $\alpha$ is some number such that $\alpha^n = a $. Well first of all, I want a $\underline{"good basis"}$ for the splitting field. In the sense that the minimal polynomials, of the adjoined elements, are different (in this case the computation of the galois group is very simple).  For example one easy case, it's when $a>0$, then $(a)^{\frac{1}{n}} \in \mathbb{R}$ , so clearly the minimal polynomial of $(a)^{\frac{1}{n}} , \zeta_n$ are distincs, and I'm done. If $n$ is odd then , it's also easy, since one root it's also real, for example $x^3-3 $, the real root is $ \root 3 \of { - 3}  =  - \root 3 \of 3  $ , so I can consider the splitting field as $\mathbb{Q}(-\root 3 \of 3 , \zeta_3 )=\mathbb{Q}(\root 3 \of 3 , \zeta_3 )$. The difficult case is when $n$ is even and $a<0$ , for example  $x^8+20$ or $x^4+20$ in some cases as in the second, there are particular cases since there exist algorithms for the Galois group of quartics, but in general. It can be done?  $\underline{Remark}$ I'm searching a $\underline{"good basis"}$ for the splitting field. In the sense that the minimal polynomials, of the adjoined elements, are different since in this case the computation of the galois group is very simple.


Are there only finitely many complex numbers $z$ with $|z|=1$? I think there are infinitely many such numbers.

There are infinitely many complex numbers $z$ such that $|z|= 1$. Can anybody just explain this to me so I can get the picture.


So let's say you find a small amount of numbered collectibles (e.g. 3 collectibles numbered 5, 14 and 103). Is there a way to estimate the total number of collectibles in existence?

Suppose that I observe $k=4$ tanks with serial numbers $2,6,7,14$.   What is the best estimate for the total number of tanks $n$?   I assume the observations are drawn from a discrete uniform distribution with the interval $[1,n]$. I know that for a $[0,1]$ interval the expected maximum draw $m$ for $k$ draws is  $1 - (1/(1+k))$. So I estimate $\frac {k}{k+1}$$(n-1)≈$ $m$, rearranged so $n≈$ $\frac {k+1 }{k}$$m+1$.  But the frequentist estimate from  is defined as:  $n ≈ m-1 + $$\frac {m}{k}$  I suspect there is some flaw in the way I have extrapolated from one interval to another, but I would welcome an explanation of why I have gone wrong!


I am having issues with my scene. I created a sand dune sort of mesh and everything is all good. I add in an HDRI and then get this:  As you can see, the sand has some sort of weird shading issue which I believe is called "shadow terminator artifacts". I've only seen three solutions:  Up the mesh density (didnt' work, even with my high poly 1mil mesh i got these artifacts) use the shadow terminator removal tool in blender 2.9 (Also didn't work, the shadows became too large) Disable smooth shading. (Did absolutely nothing)  I honestly am confused and have no idea how to fix this. The scene is literally just an HDRI rotated around slightly. One thing i will note, is that the shading issue goes away when i have a more diffuse HDRI (or none at all)  And here is everything in the viewport:  I also have tried switching out the HDRI for something else and still got the artifacts. What else can I try? EDIT: forgot to mention, I don't get this issue when I render with EEVEE.

I've been modeling a hermit crab and I don't know why but some areas of the mesh are really dark on some spots, like the legs and the claws.   I hope you can help me fix it.


This has been a really great confusion for me now ....  Many places I have read in books that when a potential difference is applied across the ends of a wire a constant electric field is generated inside it which drives the current through it...  My question is how is this electric field generated? Why is it constant in magnitude throughout the wire? What is the mechanism of flow of current inside the wire?  And  What all things happen inside the conductor just after closing the switch and before the low of constant current through it?

As I remembered, at the 2 poles of a battery, positive or negative electric charges are gathered. So there'll be electric field existing inside the battery. This filed is neutralized by the chemical power of the battery so the electric charges will stay at the poles.  Since there are electric charges at both poles, there must also be electric fields outside the battery. What happens when we connect a metal wire between the 2 poles of a battery? I vaguely remembered that the wire has the ability to constrain and reshape the electric field and keep it within the wire, maybe like an electric field tube. But is that true?


Is the one year limited warranty provided by Apple with a MacBook Pro international?  If I buy the MacBook Pro from US and use it in India, will the limited warranty be applicable in India?

I'm about to travel to the US, where iPods / AirPods / iPhone are much cheaper than in my country.   I wonder if Apple's warranty is international, and/or what warranty coverage exists when I return to my country.  Where can I understand what Apple Warranty covers in the US when products leave the US?


Currently I am reading Sean Carrol, general relativity. But a thing got me stuck in, I can't understand what he is talking about. We are discussing the introduction to Einstein field equation, so he start talk about the linearity in Newtonian gravity and the non linearity in GR. But there is somethings I am missing:  " (...) in GR the gravitational field couples to itself (...) A nice way to think about this is provided by Feynman diagrams (...) There is no diagram in which two photons exchange another photons between themselves, because electromagnetism is linear."  Particularly, I can't understand these citations. First I am not sure what means a field to couples to itself, but I think it means it is linearity so the field in a point add linearity. And I couldn't understand how does the fact that that the electromagnetism is linear imply that photons do not exchange photons between, I can see these both statements are right, but can't see the connection between them, so that one implies the other.

I have heard that non-linearity of  has to do with the fact that gravity self-couples. What does non-linearity have to do with self-coupling?


I need to find how many ways there are to choose countable subset from $\mathbb R$ the set of real numbers. This confuse me because $\mathbb R$ is uncountable, although he has countable subsets like Netural Numbers set.

More generally, if a set $S$ has cardinality $\mathfrak{m}$, how many of its subsets have cardinality $\mathfrak{n}$? Clearly there are at least $2^\mathfrak{n}$ such subsets. I don't see how many more though.  Thanks


Great Weapon Fighting states:     When you roll a 1 or 2 on a damage die for an attack you make with a melee weapon that you are wielding with two hands, you can reroll the die and must use the new roll (PHB pg.72).   A player in my game asked if this applies to the extra damage done with the Battle Master maneuvers.  Since these powers specifically word this damage benefit as:      You add the superiority die to the attack's damage roll (PHB pg.74).   I ruled that Great Weapon Fighting applies only to a "damage die" roll and not to a "superiority die" roll.  Did I get this right? Or should the Superiority Die be considered a Damage Die?

This has been a point of some controversy within our local AL community, with different DMs giving different rulings. From what I could see, this site has only touched on the Maneuver/Smite issue, with, according to some of my DMs, an out of date answer.  This also leaves the problem of extra dice on magical weapons such as an Ild rune or Hazirawn, maneuver damage dice given by another player through Commander's Strike, damage dice given by a College of Valor bard, Sneak Attack dice, and likely others which currently escape my mind.  Which damage dice exactly does the Great Weapon Fighting fighting style allow you to reroll?


The commands for Operators aren't working on realms in Minecraft. We've reset the server, de-opped and re-opped. It doesn't work. If anyone knows any reason or fix for this please let me know. We were developing our new map and now we can't do much to it...

I am an operator (OP) on my friends Realm. Today I tried to play and noticed that no commands would work for me, or anyone else granted OP. They only worked for the owner of said realm.   He has de-oped us and re-oped us with no cure to the problem. What's causing this?   Also another problem that when he tries to reload the realm it fails every single time, any options that would fix this problem?


Hatcher's algebraic topology (p. 14) defines that a pair $(X, A)$ where $X$ is a topological space and $A$ an arbitrary subset has the homotopy extension property (HEP) if:     Given a continuous map $f : X \to Z$ to some topological space $X$ and a homotopy $\bar{H}: A \times I \to Z$ of $f|_A$ on $A$ there exists a homotopy $H: X \times I \to Z$ of $f$ such that $H|_{I \times A} = \bar{H}$   (We use the notation $I = [0, 1]$) The book then proceeds to given an equivalent characterization of this property as:     There exists a retraction $r: X \times I \to X \times \{0\} \cup A \times I$   Let's call this condition (R). It's easy to prove (HEP) $\Rightarrow$ (R) and (R) $\Rightarrow$ (HEP) to be pretty easy, too: $(x, 0) \mapsto f(x)$ and $\bar{H}$ as in (HEP) agree on $X \times \{0\} \cap A \times I = A \times \{0\}$, so they glue to a map $F: X \times \{0\} \cup A \times I \to Z$ which we can compose with the retract $r$ from (R) to obtain the desired extension $H: X \times I \to Z$.  However, there is one caveat: The glue map $F$ need not be continuous.   For example, for $X = [0, 1]$, $A = [0, 1)$ and $Z = \mathbb{R}$ we can choose $f$ to be constant $0$ on $[0, 1]$ and $H : [0, 1) \times [0, 1] \to \mathbb{R}$ to be given by $H(x, t) = t/x$. Obviously $H$ can not be extended to $[0, 1]^2$. Note however, that this pair $(X, A)$ does not admit a retraction $r: X \to A$.  Questions: Is the claim (R) $\Rightarrow$ (HEP) in Hatcher correct? That is, can we somehow use the existence of the retraction $r$ to conclude that the glued map $F$ is continuous, or at least that $F \circ r$ is continuous?  If the answer is negative, what are some conditions we can impose on $X$ or $A$ to ensure the equivalence?  What I've got so far:    Obviously, if $A$ is closed the continuity of $F$ is guaranteed. If $X$ is compact, the existence of the retraction $r$ together with the compactness of $X \times I$ implies that $X \times \{0\} \cup A \times I$ and hence also $A$ are closed. If $X$ is Hausdorff, (R) also implies that $A$ is closed: Suppose $x \in \overline{A} \setminus A$. Then $r(x) \neq x$ and since $X \times I$ is Hausdorff, we find disjoint open subsets $U, V \subset X \times I$ such that $x \in U$ and $r(x) \in V$. Since $x$ is in the closure of $A$, the open set $U \cap r^{-1}(V)$ contains a point of $A$ which is then not mapped to itself by $r$, contradicting that $r$ is a retraction.

A pair $(X,A)$ of topological spaces is said to have the homotopic extension property if $\forall Y$ topological space, $f:X-> Y$ continuous map and $H:A\times[0,1]\rightarrow Y$ homotopy of $f$, there exists $\tilde H : X\times[0,1]\rightarrow Y$ extending H.   In class we gave the following lemma:  $(X,A)$ has the h.e.p. $\Leftrightarrow X\times[0,1]$ retracts onto $(X\times\{0\})\ \cup\ (A\times[0,1])$  I think I need $A$ to be closed for this to work but I am probably wrong, so I'll sketch my argument for "$\Leftarrow$" so maybe someone can spot my mistake.   If $r$ is said retraction, in class we simply defined $\tilde H$ to be $f\circ r$ for on $r^{-1}(X\times \{0\})$ and $H\circ f$ on $r^{-1}(A\times[0,1])$ and then claimed that this is well defined. However, I can't see how this function would be continuous if not by using the gluing lemma, which needs A to be closed in X.   Am I missing something?  Thank you.


Suppose $G,G'$ are groups and $\phi:G\to G'$ is an isomorphism. Show that $g$ is a generator of $G$ implies $\phi(g)$ is a generator of $G'$

Qusetion: Prove $\phi(G)$ is cyclic if $\phi$ : $G \to H$ is  group homomorphism and $G$ is cyclicDo I do something like this to prove this: Let $G$ be a cyclic group and $G$=$\langle g \rangle$Then $\phi$ : $\mathbb Z \to \langle g \rangle$ by $\phi(n)$= $g^{n}$, $n\in \mathbb Z$ I am not sure of my approach to this. Need some help


I want to have my Stack Exchange flair on all stack exchange websites. Is that possible? Can it be implemented?

I have seen some users show a picture of their network profile on the profile tab. How can I add this for my own account?


I'm trying to move a Java project I've made and tested to Android. My problem appears when I create the Socket with the Strings for the IP and port (which are not null and correspond to the IP of an open and working server). A NullPointerException appears. The code is an AsyncTask that is activated when the user presses a button. This is the doInBackground method:  @Override protected Void doInBackground(String... strings) {     client = new Client(strings[0]);     DataStorage.getInstance().setClient(client);      try {         boolean a = client.connectToServer(strings[0]); //It dies here         if (!(un).equals("")&&a) {             Toast.makeText(context,"Connected",Toast.LENGTH_SHORT).show();              Intent intent = new Intent(context, AvailableClientsActivity.class);             context.startActivity(intent);          } else {             Toast.makeText(context,"Username invalid",Toast.LENGTH_SHORT).show();         }     } catch (UnknownHostException e) {         e.printStackTrace();     } catch (IOException e) {         client.resetConnection();     }      return null; }   This is the message I get Method threw 'java.lang.NullPointerException' exception. Cannot evalueate android.system.StructAddrinfo.toString()  I've just started with Android so it might be something basic I've skipped.

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


i am using hp ay503tx there is A problem with my wifi , wifi is detecting the networks but not all available neworks . and couldn't connect with them   my network detail is   *-network             description: Wireless interface             product: RTL8723BE PCIe Wireless Network Adapter             vendor: Realtek Semiconductor Co., Ltd.             physical id: 0             bus info: pci@0000:03:00.0             logical name: wlo1             version: 00             serial: 3c:a0:67:76:a9:b5             width: 64 bits             clock: 33MHz             capabilities: bus_master cap_list ethernet physical wireless             configuration: broadcast=yes driver=rtl8723be driverversion=4.10.0-33-generic firmware=N/A ip=192.168.43.165 latency=0 link=yes multicast=yes wireless=IEEE 802.11             resources: irq:17 ioport:3000(size=256) memory:b1100000-b1103fff

I have a HP 14-AN001NA laptop. It came with Windows 10 installed on which the Wi-Fi worked fine anywhere in the house.   However I removed Windows 10 and installed Ubuntu 16.04 instead and since I have had terrible Wi-Fi anywhere aside from about three foot away from the router. I don't know if it's relevant but my Wi-Fi is not called wlan0 but wlo1 for some reason (I didn't change it).  When running lspci -knn | grep Net -A3     I get the following output:  05:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8723BE PCIe Wireless Network Adapter [10ec:b723] DeviceName:   Subsystem: Hewlett-Packard Company RTL8723BE PCIe Wireless Network Adapter [103c:81c1] Kernel driver in use: rtl8723be Kernel modules: wl, rtl8723be


The question is to find out the value of $a$ such that $ax^2-4x+9=0$ has integer roots.  If $a$ is 1 then the roots if they are rational are integers.But the discriminant in such case is -ve so $a\neq 1$ Similarly by rational root theorem $a \neq -1$ So $a$ must be a fraction of the form $1/b$ such that $b$ is a integer. Now the condition of the equation $x^2-4bx+9b$ to have rational roots and thereby integers because the leading coefficient is unity is that its discriminant must be a perfect square.so $16b^2-36b$ is a perfect square.I couldn't get how to determine $b$ from this.Any ideas?Thanks   This link  doesn't have the attempt in which I am unable to proceed.

Find the value(s) of $a$ for which the equation   $ax^2-4x+9=0$   has integral roots(i.e. $x$ is an integer).  My attempt:   By hit and trial I am getting answer as $a=\frac{1}{3}$. No information about nature of $a$ is given.


I tried to make a function that takes one argument (a number) and returns true/false if it has 6 inside of it. I know how to do that in python. In python it should look like this: def six(num):     num=str(num)     return "6" in num  How do I do it in Java?

In Java is there a way to check the condition:  "Does this single character appear at all in string x"  without using a loop?


I conducted One-Way ANOVA to compare means in 4 groups. The ANOVA was significant, but the post hoc tests were non-significant. Then, I applied unpair t-tests to compare each group to the lowest group. The unpair t-tests were significant. So, is it reasonable to meet something like this, and if yes, why? I would appreciate any try of help as I am a beginner in statistic and confused.

Is it possible for one-way (with $N>2$ groups, or "levels") ANOVA to report a significant difference when none of the $N(N-1)/2$ pairwise t-tests does?   In  @whuber wrote:      It is well known that a global ANOVA F test can detect a difference of means even in cases where no individual [unadjusted pairwise] t-test of any of the pairs of means will yield a significant result.   so apparently it is possible, but I do not understand how. When does it happen and what the intuition behind such a case would be? Maybe somebody can provide a simple toy example of such a situation?  Some further remarks:   The opposite is clearly possible: overall ANOVA can be non-significant while some of the pairwise t-tests erroneously report significant differences (i.e. those would be false positives). My question is about standard, non-adjusted for multiple comparisons t-tests. If adjusted tests are used (like e.g. Tukey's HSD procedure), then it is possible that none of them turns out to be significant even though the overall ANOVA is. This is covered here in several questions, e.g.  and . Update. My question originally referred to the usual two-sample pairwise t-tests. However, as @whuber pointed out in the comments, in the ANOVA context, t-tests are usually understood as post hoc contrasts using the ANOVA estimate of the within-group variance, pooled across all groups (which is not what happens in a two-sample t-test). So there are actually two different versions of my question, and the answer to both of them turns out to be positive. See below.


I am working with a compromised Ubuntu 8.04 Plesk 9.5.4 server. It seems that a script on the server is continuously doing reverse lookups to random IPs on the Internet.  I first spotted it during by using top and then noticed flashes of this coming up continuously: sh -c host -W 1 '198.204.241.10'  I wrote a this script to interrogate ps every 1 second to see how frequently this script happens:  #!/bin/bash while : do     ps -ef | egrep -i "sh -c host"     sleep 1 done   The results are that this script runs often, every few seconds:  www-data 17762  8332  1 10:07 ?        00:00:00 sh -c host -W 1 '59.58.139.134' www-data 17772  8332  1 10:07 ?        00:00:00 sh -c host -W 1 '59.58.139.134' www-data 17879 17869  0 10:07 ?        00:00:00 sh -c host -W 1 '198.204.241.10' www-data 17879 17869  1 10:07 ?        00:00:00 sh -c host -W 1 '198.204.241.10' www-data 17879 17869  0 10:07 ?        00:00:00 sh -c host -W 1 '198.204.241.10' root     18031 17756  0 10:07 pts/2    00:00:00 egrep -i sh -c host www-data 18078 16704  0 10:07 ?        00:00:00 sh -c host -W 1 '59.58.139.134' www-data 18125 17996  0 10:07 ?        00:00:00 sh -c host -W 1 '91.124.51.65' root     18131 17756  0 10:07 pts/2    00:00:00 egrep -i sh -c host www-data 18137 17869  0 10:07 ?        00:00:00 sh -c host -W 1 '198.204.241.10' www-data 18137 17869  1 10:07 ?        00:00:00 sh -c host -W 1 '198.204.241.10'   My theory is if I can see who is launching the sh process or form where it's launched I can isolate the problem further.  Can somebody please guide me using netstat or ps to identify from where sh is being run?  I might get many suggestions that the OS is out of date and so the Plesk, but please bear in mind there are some very concrete reasons why this server is running legacy software. My question is aimed at a advanced Linux systems administrators who have in depth experience with security compromises and using netstat and ps to get to the bottom of it.  UPDATE 26 Oct 14:01 SAST  The command grep -lr 'sh -c host' left in the comments left by @ramruma helped me to quickly find the corresponding website running the script. As it turns out the server is not compromised. What is instead happening is there is a forum in that location produced by Powered by SMF 1.1.2 | SMF © 2006-2007, Simple Machines LLC that does a reverse lookup every time someone accesses the board.  It also turns out that the forum is unmaintained and severely spammed and why we initially thought it's compromised is because many of the reverse lookups pointed to foreign IPs known for spamming. Goodness only knows how a website can execute this command, but for the time being I am going to close the issue as harmless.  With regards to the blanket replies I received about "restore from backup" I came to ServerFault to help isolate the issue and I made it clear in my initial request. Sometimes restoring from backup is impractical or even impossible. It's better to figure out the issue or find the compromise in case it might arise in the future.

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


Because of the recently announced bash environment variable vulnerability, I chose this evening to upgrade my headless server from 13.10 to 14.04 - saucy to trusty.  Upon running sudo shutdown -r now after the upgrade finished, it didn't come back up.  I've just spent several hours finding a graphics card to fit in the server, and dragging a monitor up to it, to find out the following:   the grub menu doesn't appear to have a default timeout (I waited a couple of minutes) the eys (sp?) service is asking me interactive questions about mounting partitions when it can't find the source drive - "press s to skip mounting or m for manual recovery"   Now, I can solve the first problem easily enough - reconfigure grub with a timeout, I'll be sure to check it manually after my next OS upgrade.  The second problem should go away after I take out the graphics card and plug my HBA back in.  But the very fact that it's asking me a question is problematic. I don't want any interactive questions to be asked on startup. And I don't want OS upgrades to be adding interactive steps to the boot process.  Is there some flag or setting I'm missing that lets Ubuntu, its upgrade machinery and utilities know that my machine is headless, and the user should not be asked interactive questions or presented with menus without timeouts?

After upgrading my laptop from karmic to lucid, my fat32 partition won't mount automatically. I get the message:  The disk drive for /osshare is not ready yet or not present Continue to wait; or Press S to skip mounting or M for manual recovery   Funny thing is, if I skip, then /osshare/ is mounted once I log in.   I've a similar setup on my desktop, and it works fine. Fstab on desktop:  UUID=4663-6853  /osshare        vfat    utf8,umask=007,gid=46 0       1   /etc/fstab on laptop:  UUID=1234-5678 /osshare vfat utf8,auto,rw,user 0 0


I'm trying to get the name of the property that's been affected by a driver for a certain object, what I did so far:  for d in bpy.context.object.animation_data.drivers:     print(d.driver.id_data.name)  However, that's returning the name of the object, not the driven property. My question is, let's say there's a drive controlling the Z Scale, how do I get that information "Z Scale" or a similar equivalent, in scripting?

How can I find out all properties that a driver is driving without manually checking every object in the graph editor?


Today in class, the instructor is trying to show that for $n \ge 0$, $n < 2^n$. And this are the steps he took:  First we assume the inductive hypothesis i.e. $0 < 2^0$, and this is true. Then to prove that for any arbitrary integer $k \ge 0$, $k < 2^k$. The proof proceeds as follows:   Assume $k < 2^k$ is true for $k ge 0$. Show that $(k + 1) < 2 ^{k + 1}$. By induction hypothesis, $k < 2^k$ thus $k + 1 < 2^k + 1 < 2^k + 2^k = 2^{k + 1}$.   Thus by mathematical induction the result has been proven  My question now is how was step 3 derived? Where does the extra $2^k$ manifest from?

I'm trying to do homework problems and for the most part I've been getting the results. For this one though, I am having some trouble since its $2^n$ and I can't relate it properly:     Prove using simple induction that $n < 2^n$ for all $n \ge 1$.   So obviously, the basis step holds as $1 < 3$. Now, I assume that $n = k$ holds as well and have to prove for $n=k+1$. This is the step I am having trouble with as I cannot relate the induction hypothesis with what I want to end up with. Can anybody show me a model solution for this one? I think my trouble comes because of the $2^n $


I can reclaim the reserved space on the system partition (/dev/sda1), but the /home partition (/dev/sda2) doesn't let me free it up, and I really need it because it's almost 42GB I'm not using. This is the error I get:  tune2fs 1.42.13 (17-May-2015) tune2fs: Filesystem has unsupported read-only feature(s) while trying to open /dev/sda2 Couldn't find valid filesystem superblock.   I tried looking up other solutions, but I didn't see any relevent solution specifically concerning this issue. Any help is appreciated.

I did a fresh install of Ubuntu 16.04. /dev/md1 contains an ext4 filesystem that is mounted at /:  /dev/md1 on / type ext4 (rw,relatime,data=ordered)   Now I want to set the automatic filesystem check interval to one month, but I'm getting a strange error that I find no useful information about:  > tune2fs -i 1m /dev/md1 tune2fs 1.42.13 (17-May-2015) tune2fs: Filesystem has unsupported read-only feature(s) while trying to open /dev/md1 Couldn't find valid filesystem superblock.   Rebooting didn't help. On another machine running Ubuntu 12.04, the same command works like a charm.  Does anyone have an idea what's wrong?  The command tune2fs -l /dev/md1 works fine, by the way. Here is its output:  tune2fs 1.42.13 (17-May-2015) Filesystem volume name:   <none> Last mounted on:          / Filesystem UUID:          38366a40-bbe1-476b-acfe-d271be6335eb Filesystem magic number:  0xEF53 Filesystem revision #:    1 (dynamic) Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg sparse_super large_file huge_file dir_nlink extra_isize metadata_csum Filesystem flags:         signed_directory_hash Default mount options:    user_xattr acl Filesystem state:         clean Errors behavior:          Continue Filesystem OS type:       Linux Inode count:              8380416 Block count:              33521664 Reserved block count:     1676083 Free blocks:              32419430 Free inodes:              8312762 First block:              0 Block size:               4096 Fragment size:            4096 Group descriptor size:    64 Reserved GDT blocks:      1024 Blocks per group:         32768 Fragments per group:      32768 Inodes per group:         8192 Inode blocks per group:   512 Flex block group size:    16 Filesystem created:       Thu May 31 10:01:27 2018 Last mount time:          Thu May 31 10:49:41 2018 Last write time:          Thu May 31 10:15:14 2018 Mount count:              7 Maximum mount count:      -1 Last checked:             Thu May 31 10:01:27 2018 Check interval:           0 (<none>) Lifetime writes:          5782 MB Reserved blocks uid:      0 (user root) Reserved blocks gid:      0 (group root) First inode:              11 Inode size:               256 Required extra isize:     32 Desired extra isize:      32 Journal inode:            8 First orphan inode:       4325378 Default directory hash:   half_md4 Directory Hash Seed:      9d55d989-2c2b-4ad8-a29e-53c8798ec68e Journal backup:           inode blocks Checksum:                 0x3d9f8d23


I was wondering how to fix these corrupted files I've downloaded. They're in parts, and part 5 and 11 are corrupt. I can't extract the whole file.  I already tried to repair it using WinRAR repair.

I try to extract a file from set of .RAR parts. I always get the following error:  Corrupted   so I tried many programs to extract the corrupted RAR files. I have 10 parts, each one 400MB big. The last progam I used was .  It gave me the following message:     Severity:!High   Message:Recovery error for file XXXX with message set file   pointer error.   The program extracted 2GB of data, but it should extract 4GB.    Is there any way to extract the content or am I supposed to download the files again from another server?


Came across using !! in C++ during condition check if ( !! (flag != 0 )){.. }  This could be directly used like if( flag != 0 ){.. }    Is there any specific corner use case in C/C++ or is it just a form of coding style ?

I just came onto a project with a pretty huge code base.   I'm mostly dealing with C++ and a lot of the code they write uses double negation for their boolean logic.    if (!!variable && (!!api.lookup("some-string"))) {        do_some_stuff();  }                                      I know these guys are intelligent programmers, it's obvious they aren't doing this by accident.   I'm no seasoned C++ expert, my only guess at why they are doing this is that they want to make absolutely positive that the value being evaluated is the actual boolean representation. So they negate it, then negate that again to get it back to its actual boolean value.   Is this correct, or am I missing something?


My new Macbook pro 13 inch 256 GB (Early 2015)  Storage Apps more than 800 GB on 256 GB SSD    with scan by DaisyDisk Apps 30 GB

With no good reason I had a look at my computer's storage going on the apple and About this Mac. Here is the display:    The pink bar doesn't make much sense. It obviously does not represent the 80.67GB of free storage. Two sections correspond to pink; "Photos" and "Backups". I obviously don't have 140.76TB of backups. And probably not on this computer that has only 320GB of storage.  What is going on here?


When I activate the Freestyle setting in the render tab for my 3D objects and render it, the render of the lines are on top of my other grease pencil objects and intersects them in an unwanted way. Is there a way to fix this? i've tried to change the origin point for all of the  3D and 2D objects but that did not fix it. Sorry if i'm not explaining the problem well, I'm happy to try and explain more. I'm using Blender 2.93(beta) and the freestyle has a noise and a thickness modifier. thank you for any suggestions.

I’ve been trying to render a grease pencil drawing on top of a Freestyle rendered object. But, when I do it the Freestyle lines can be seen behind the Grease Pencil object. Is there a way to solve this?  I made an example with a blue circle made with Grease Pencil, in front of a cube rendered with Freestyle.  I’ve tried using Eevee, Cycles and Benchmark.  Thanks in advance.  Viewport:    Render:


In python 2 i have this simple loop   while True:     for i in ["/", "-", "|", "\\", "|"]:         print "%s\r" % i,   It produces a loop of those symbols, on the same line, replacing each character in place (so you never see more than 1 symbol)  However, in python3  while True:     for i in ["/", "-", "|", "\\", "|"]:         print("%s\r" % i,)   The same code, when fixed for syntax, prints each symbol on a new line  Not sure what I am missing, would appreciate the help

I'd like to do it in Python. What I'd like to do in this example in C: #include <stdio.h>  int main() {     int i;     for (i=0; i<10; i++) printf(".");     return 0; }  Output: ..........  In Python: >>> for i in range(10): print('.') . . . . . . . . . . >>> print('.', '.', '.', '.', '.', '.', '.', '.', '.', '.') . . . . . . . . . .  In Python print will add a \n or space, how can I avoid that? Now, it's just an example, don't tell me I can first build a string then print it. I'd like to know how to "append" strings to stdout.


I am collaborating with another person on a paper and I was wondering if we are suppose to write our advisor's name in our papers merely because they funded us and looked over the paper?

I understand that in a lot of big-lab fields it is common for the principal investigator to append their name to a paper even if they did not write the paper, design the experiment, or collect data since they spend energy securing funding, and managing the whole lab. What about for small labs?  What are the requirements for a supervisor to be included as an author on a paper, as opposed to just appearing in the acknowledgements? If you are working on your own projects independently of your supervisor, but using funding provided by your supervisor (how does this change when the funding provides resources versus just your salary), are you suppose to add them as authors or just acknowledge the source of funding?


Let f(t)=2/(t+8)  (a) Simplify the following difference quotient as much as possible:  [f(t+h)−f(t)]/h  MY ANSWER (CORRECT): −2/[(t+8)(t+h+8)]  (b) Use your result from (a) and the limit definition of the derivative to calculate  f'(t)=lim_h→zero [f(t+h)−f(t)]/h=  MY ANSWER (CORRECT): −2/[(t+8)^2]  (c) Use your answer from part (b) to evaluate  f'(−3)  MY ANSWER (CORRECT): −2/25  (d) Find the equation of the tangent line to the curve at the point  (−3,f(−3))  y= ?  I have tried the point-slope formula, y−y_1=m(x−x_1), but my answer was incorrect.

Let f(t)=2/(t+8)  (a) Simplify the following difference quotient as much as possible: $$[f(t+h)−f(t)]/h$$  MY ANSWER (CORRECT): $-2 / [(t+8)(t+h+8)]$  (b) Use your result from (a) and the limit definition of the derivative to calculate $f′(t)=\lim_{h → 0} [f(t+h)−f(t)]/h=$  MY ANSWER (CORRECT): $-2 / [(t+8)^2]$  (c) Use your answer from part (b) to evaluate $f′(−3)$  MY ANSWER (CORRECT): $-2 / 25$  (d) Find the equation of the tangent line to the curve at the point $(−3,f(−3))$ y=  I have tried the point-slope formula, $y-y_1=m(x-x_1)$, but my answer was incorrect.


import java.util.Scanner;   public class Methods {  /*  * Compound interest Program Quarterly  */       public static void main(String[] args) {         Scanner keyboard = new Scanner  (System.in);          System.out.println("What is the Rate");         int rate = keyboard.nextInt()/100;         System.out.println("What is the Amount");         int amount = keyboard.nextInt();         System.out.println("How many years?");         int years = keyboard.nextInt();          keyboard.nextLine();         System.out.println("How is it compounded? Press Q = Quarterly, A = Anually, S = SemiAnnualy, M = Monthly");          String answer = keyboard.nextLine();         int easy = amount*(1+(rate/years));        int pow = 4 * years;           if (answer == "/Q"){             System.out.println("Your answer compounded Quarterly is: "  + Math.pow(easy,pow));   This is the code, but the if statement with String == "Q" doesn't work because when I press Q nothing happens? what's the issue?

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Let say $a_0, a_1, ..., a_k$ are a series of positive integers, with $k > 0$, if one of the number has irrational square root, $\sqrt{a_n}$, such as $\sqrt{2}$, or $\sqrt{3}$, there is not way we can find a series of $a_0, ..., a_k$ to make  $$\sqrt{a_0}+ \sqrt{a_1} + \sqrt{a_2}+ ... + \sqrt{a_k}$$ is an integer.  Is this assumption correct? Is there a theorem for this? Thanks.

Is it true that all numbers of the form $\sqrt[b_1]{a_1}+\sqrt[b_2]{a_2}+\cdots+\sqrt[b_k]{a_k}$ are not integers, where $a_i,b_i$ are positive integers such that none of the $k$ terms is an integer? I think this must be a theorem somewhere, probably a fundamental theorem in number theory, but not sure what it would be called.


How does tar.gz file gets uncompressed with all contents to arbitrary directory, existing or not using tar using single line command? If it does not exists, then is created (directory). To clarify, let consider example: I've downloaded archive-latest.tar.gz from internet into directory /home/user/Downloads. I have microSD card target partition mounted on /mnt/archive. Once downloaded, I want to extract downloaded /home/user/Downloads/archive-latest.tar.gz directly on /mnt/archive using single line command. I've read man tar manual, but I cannot find option for specifying target dir.

This doesn't work:  tar xf /tmp/foo.tar.gz foo/bar tar: foo/bar: Not found in archive   It's not obvious to me what would do this beyond extracting it in place and moving the files over.


I have two columns (groupID, memberID) in table and I execute following mysql query select `groupID` from `tbl_groupassign` where `memberID` = 'check1';  which prints column groupID but I want to show groupID in single row with each groupID separated by comma. For example I get following result by executing above query  groupID group1 group2  but I want show it as group1, group2

Using MySQL, I can do something like:  SELECT hobbies FROM peoples_hobbies WHERE person_id = 5;   My Output:  shopping fishing coding   but instead I just want 1 row, 1 col:  Expected Output:  shopping, fishing, coding   The reason is that I'm selecting multiple values from multiple tables, and after all the joins I've got a lot more rows than I'd like.  I've looked for a function on  and it doesn't look like the CONCAT or CONCAT_WS functions accept result sets.  So does anyone here know how to do this?


I apologize for repeating my question, but it was suggested that I ask it on this StackExchange site instead of stackoverflow:  :  I have created a simple .NET 4.5 Entity Framework Winforms application with Visual Studio and would like to open it on OS X.  I have used Wine before to open .exe's in the past and am having difficulty this time around. I have downloaded the most recent version of Wine, as well as OS X.  When I attempt to open the .exe with Wine, nothing happens. No error messages. Nothing.  When I attempt to package the .exe with WineBottler, I get a popup that says "Prefix created successfully"; however, when I attempt to open the newly created file, again, nothing happens.  I am very new to using Wine and have noticed that there are WineTricks you can use, but I am not sure if that is necessary. Again, I used Wine before on a very simple app and it worked just fine without using any WineTricks, but I am not sure whether I should include them for this app.  I have googled for help, but have not found much. Any assistance is greatly appreciated!

Running macOS Sierra(Version 10.12.2 16C67).  I installed  version wine-1.8.6 (through a .pkg file). I opened up a game and it worked fine.  The next day when I downloaded Origin installer, it wouldn't open. When I double clicked on it, the Wine icon showed up in the dock and said it was open, but no windows showed up. When I clicked on another program(or on the desktop), Wine closed. Now when I try to start that same game I opened when I first installed Wine, the same thing happens that happened when I started Origin installer.  When I go to the terminal and type wine {path of .exe} I got this:   I installed wine tricks using brew install winetricks and it installed fine, yet it didn't change my situation.  winecfg works properly, and so does sh winetricks.


Assume that $A$ and $B$ are both $n\times n$ matrices, how would I prove that $(A + B)^2 = A^2 + 2AB + B^2$ for any $n\times n$ matrices?

We know that in matrices AB=BA.Why in this Matrices $A=\begin{bmatrix} -1 & 3\\  2 & 0\end{bmatrix}$, $B=\begin{bmatrix} 1 & 2\\ -3 & -5\end{bmatrix}$ are not equal to $AB=BA$. WHY? This is matrix  of order $2\times 2$ for both $A$ and $B$.


Sometimes, I saw the following code:  if ( !!on_debugging )    which is the same as  if ( on_debugging )   I don't understand why these two !s are used. Is there any kind of difference?

I just came onto a project with a pretty huge code base.   I'm mostly dealing with C++ and a lot of the code they write uses double negation for their boolean logic.    if (!!variable && (!!api.lookup("some-string"))) {        do_some_stuff();  }                                      I know these guys are intelligent programmers, it's obvious they aren't doing this by accident.   I'm no seasoned C++ expert, my only guess at why they are doing this is that they want to make absolutely positive that the value being evaluated is the actual boolean representation. So they negate it, then negate that again to get it back to its actual boolean value.   Is this correct, or am I missing something?


I work with TextMate and R over the terminal. When pasting a lot of code (CMD+C/CMD+V, e.g. 60 lines) it sometimes happens that few characters in the code are scrambled, which then leads to error messages and wrong code execution.  For example:     col <- ifelse(...   is turning into      col < col < cse(...   or      onlyDF   is turning into     oalyDF   These character-replacements seem very random and it is difficult to predict when it happens.  The problem is also described here for iterm2:   The explanation provided there is that it is a bug in bash that can lead to buffered input to get lost due to paste speed.   Has anyone experienced these problems and found a work-around for the native terminal app in Mac OS? (e.g. by modifying the paste speed, if that is possible in terminal)

If I paste multiline chunks of text into iTerm2, I always a get mess of output. It seems limited to only some programs running interactively (such as Bash, IRB - Python / VIM work flawlessly). Using Apple's native Terminal, I can paste whatever I want wherever I want - it works. For example, this sample text ():  echo Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec a diam lectus. echo Sed sit amet ipsum mauris. Maecenas congue ligula ac quam viverra nec consectetur ante hendrerit. echo Donec et mollis dolor. Praesent et diam eget libero egestas mattis sit amet vitae augue. echo Nam tincidunt congue enim, ut porta lorem lacinia consectetur. Donec ut libero sed arcu vehicula ultricies a non tortor. echo Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean ut gravida lorem. Ut turpis felis, pulvinar a semper sed, adipiscing id dolor. echo Pellentesque auctor nisi id magna consequat sagittis. Curabitur dapibus enim sit amet elit pharetra tincidunt feugiat nisl imperdiet. echo Ut convallis libero in urna ultrices accumsan. Donec sed odio eros. Donec viverra mi quis quam pulvinar at malesuada arcu rhoncus. [snip]   pasted into IRB produces this in iTerm2:    while it produces this in native Terminal:    I am running the latest versions of OSX and iTerm2. What's going wrong here?


I installed Lubuntu 12.10 PPC alt. Install on my ibook g4, yaboot failed to install so I used the advice given in the PPC FAQ, , and I was able to boot to a black screen with and move the arrow but that's all, when trying to login by pressing ctrl+alt+f1 I kept getting "invalid" login. I reinstalled and yaboot failed again, except this time I am unable to boot even to a black screen and trying to login via pressing ctrl+alt+f1 still gives me an invalid login message despite the fact I know 100% I am correctly typing in my username and password.  EDIT: For some reason, another reinstall went smoothly despite using the disc. I was able to login but had to use single user mode to reset my password as the invalid login error occurred again.

I want to change my computer's password. Right now my password is abc123. I run this command:  sudo passwd   I entered my current password and then a new one but the change does not take effect. How can I resolve this problem ?


Consider the explicit midpoint method, i.e $$y_{n+1}-y_{n-1} = 2hf(y_n).$$  I'm asked to apply this method to the linear test equation, $f(y_n) = \lambda y_n,$ in order to find the method's stability region.   So I have  $$y_{n+1}-y_{n-1} = 2h\lambda y_n.$$  In the problems I've done before I wouldn't have the $y_{n-1}$ term so I could just easily write $y_{n+1} = R(z)y_n.$ How would I solve this?

I have the following two step Nyström method: $u_{k+1}=u_{k-1}+2h\cdot f(u_k)$. I want to know the stability region, so I wrote this as $w_{k+1} = A\cdot w_k$ with $A=\left(\begin{matrix} 2h\lambda & 1 \\ 1 & 0\end{matrix}\right)$ and $w_k = (u_{k},u_{k-1})^t$. I use the sample/test equation $u'=\lambda\cdot u = f(u)$ with $\lambda\in\mathbb{C}$. To find the stability region I must set some limitations on the matrix A.  Do I want the whole vector $w_{k+1}$ to go to the zero vector as $k$ goes to infinity, or just the first component that contains $u_{k+1}$? I don't think I can let the second component go to zero, since the matrix just has a $1$ in the bottomleft corner. So I think I want $2h\lambda$ to be negative in the reals (like Forward Euler) , or at least less than 1? I'm unfortunately just guessing at this point.  For (Forward) Euler we have $u_{k+1}=u_k + h\cdot f(u_k) = (1 + h\lambda)u_k$ and so we require that $h\lambda$ does not have a positive real part.  So I guess I also want some anologue for matrices being less than 1? I do not know how to deal with the matrices since the left hand vector not only contains $u_{k+1}$ but also the old $u_k$.


There is a formula that describes this expansion using big O notation, I'm very curious on how this is derived. I also understand that the order term may very depending on what $\Delta x$ approaches to in limit ?  $(x + \Delta x)^{n} = x^{n} + nx^{n-1}\Delta x + O((\Delta x)^{2})$

I'm currently following the MIT Single Variable lectures online and the professor states that the binomial theorem for the expansion   $(x + \Delta x)^{n} = x^{n} + nx^{n-1}\Delta x + O((\Delta x)^{2})$   How is this derived, and what does the big O term of the expansion represent in terms of the binomial theorem. Just to put this in context, this expression was used when computing the derivative of $x^{n}$ using the limit definition.


Ive bought a spinning bike to help in lockdown, and its ace...I want to change the pedals to a clipless set. I bought some clipless pedals, but the thread on the pedal is way smaller than the ones coming off. I read about and bought an adapter, but its on marginally larger. Is what I'm trying to do possible, there only seem to be 2 pedal sizes and each would be way to small to fit my crank. Is it possible I have a crank that only fits its own pedal size??. Any help would be appreciated as I'm a set of pedals shoes and an adapter down at the moment. Many thanks

I’ve bought a spinning bike that has the cage pedals. I have cleat shoes which I prefer to ride in, so I bought some cleat pedals to fit to the spinning bike. Trouble is I've just taken the existing pedals off, and the thread is way bigger on the spinner pedal than the one I have on the pedals I have bought. Is there a bigger pedal or adapter available?


Before ubuntu 20.04 (at least in 18.04 I am sure) you could change the background for login screen, by editing /etc/alternatives/gdm.css, and changing the url of background image to my favourite file. but there is no such file in 20.04 How could I do this in 20.04?

How can I change the Ubuntu 20.04 login screen theme or background?  In the previous version 19.10, I can change it from the CSS file under Yaru theme but now there is no CSS file.


We all, by definition, know that $ i^2 = -1 $, but does that imply (or is it even equivalent ?) that $\sqrt{-1} = \pm i$ ? I often see debates on internet where people are arguing over this last equality, most people arguing that the square root operation is only defined for positive numbers.  I am not familiar with mathematics, so to me, both equations are equivalent, if not, could someone explain in easy terms ?

So I am about halfway through complex analysis (using Churchill amd Brown's book) right now.  I began thinking some more about the nature and behavior of $i$ and ran into some confusion.  I have seen the definition of $i$ in two different forms; $i = \sqrt{-1} $ and $i^2 = -1$.  Now I know that these two statements are not equivalent, so I am confused as to which is the 'correct' definition.  I see quite frequently that the first form is a common mistake, but then again Wolfram Math World says otherwise.  So my questions are:   What is the 'correct' definition of $i$ and why?  Or are both definitions correct and you can view the first one as a principal branch? It seems that if we are treating $i$ as the number with the property $i^2 = -1$, it is implied that we are treating $i$ as a concept and not necessarily as a "quantity"? If we are indeed treating $i$ as a concept rather than a "quantity", how would things such as $i^i$ and other equations/expressions involving $i$ be viewed?  How would such an equation have value if we treat $i$ like a concept?   I've checked around on the various imaginary number posts on this site, so please don't mark this as a duplicate.  My questions are different than those that have already been asked.


Should a lecturer say      "He felt bad" or "He felt badly"?   "His tooth ached so bad he couldn't sleep" or "His tooth ached so badly he couldn't sleep"?     Are both forms acceptable in formal speech?

What is the correct usage? Apparently it is "I feel badly", but but wouldn't that mean you have an inadequate ability to feel?


I'm a programmer, who dont know much about system administration.  I'm running a IIS php database (PostgreSQL) app on my localhost where I'm the only user. I want to make the webpages and the web server completely inaccessible from the internet. I have foreign ips in the event log. I'm worried about security as the app and computer has sensitive data. I want to shut all services down except for php for localhost access. How do I best do this?  If I could do without the inetpub\wwwroot completely that would be good, if I could get php to work in a normal local folder. Or maybe some settings (DefaultAppPool.config?) for shutting off the webserver completely to the outside world?

We've got a webserver running IIS. We'd like to run maybe a shared blog or something to keep track of information. Because of security issues, we'd like for that part to be only viewable from localhost so people have to remote in to use it.  So, to repeat my question, can part of a website be made viewable from localhost only?


The following is my code, but it didn't work, do I miss some package? Please, give me advice and correct code. Thanks for your help!  \begin{tabular}{|c|c|c|c|} \hline & x<0 & x=0 & x>0\\ \hline y<0 & x^2-y^2 & x^2+y^2 & x^2-y^2\\ \hline y=0 & x+y & x^2-y^2 & x^2+y^2 & x^2-y^2\\ \hline y>0 & x^2+y^2 & x+y & x^2+y^2\\ \hline y<0 & x^2-y^2 & x^2+y^2 & x^2-y^2 \end{tabular}

\begin{tabular}{|l|l|l|} \hline Column A & Column B \\  \begin{math} x & y \\ \end{math}  \end{tabular}   This won't let me compile and gives a lot of errors, how do I enable math mode in a table without using $ on everything?


I have produced the following code, for a graph I am making:  \usepackage{tikz} \begin{document}  \begin{figure}[h] \centering \caption{AMD top 10 SBP peers (2016)} \label{FigAMDtop10SBPpeers} \begin{tikzpicture} \begin{axis}[     ymin=0, ymax=8,     ylabel = Annual Search Fraction,     yticklabel=\pgfkeys{/pgf/number format/.cd,fixed,precision=0,zerofill}\pgfmathprintnumber{\tick}\%,     axis background/.style={fill=gray!5},     symbolic x coords={Intel,HP,Nvidia,Broadcom,Texas Instruments,Google,Microsoft,IBM},     xtick=data]     \addplot[ybar,fill={rgb:red,0;green,47;blue,135}] coordinates {         (Intel,6.1529271206690564)         (HP,1.3888888888888888)         (Nvidia,1.045400238948626)         (Broadcom,0.9557945041816009)         (Texas Instruments,0.9109916367980884)         (Google,0.6869772998805257)         (Microsoft,0.6571087216248507)         (IBM,0.6421744324970132)      }; \end{axis} \end{tikzpicture} \end{figure}   \end{document}   which looks like:     Clearly, the x-labels are not appropriate. I was wondering if there is a way to make the entire x label visible, without rotating the label (i don't like the layout)? For a firm like Texas Instruments, which has 2 words, maybe put the second word on the line below?   EDIT: The possible solution is not what I am looking for, since that merely shifts every other label downwards. This is not what I want; I want to keep the label positionings next to each other.

Is it possible to automatically change the position of every other x tick label in pgfplots?  This is my scenario: I have a plot with symbolic x tick labels loaded from the table.  Those labels are too wide to fit next to each other:    What I would like to have is that every other label is automatically shifted a bit downwards like in this example:    Minimal working code for the "bad" example:  \documentclass[a4paper]{article} \usepackage{pgfplots} \pgfplotsset{compat=1.5}  \begin{filecontents}{data.txt}   label     x y   foobarbaz 0 1   foobarbaz 1 1   foobarbaz 2 1   foobarbaz 3 1   foobarbaz 4 1 \end{filecontents}  \begin{document} \begin{tikzpicture}   \begin{axis}[       ybar,       x=1cm,       xtick=data,       xticklabels from table={data.txt}{label},     ]     \addplot table [x=x, y=y] {data.txt};   \end{axis} \end{tikzpicture} \end{document}   For the "good" one I manually added \raisebox to every other label:  \begin{filecontents}{data.txt}   label     x y   foobarbaz 0 1   \raisebox{-4ex}{foobarbaz} 1 1   foobarbaz 2 1   \raisebox{-4ex}{foobarbaz} 3 1   foobarbaz 4 1 \end{filecontents}   However, since my actual data contains much more lines, I don't want to do it manually like this. Is there a way to do this automatically with pgfplots?


I watched Episode 3½ (Rogue One) and cannot understand why the name is Rogue One? It is the name of stolen ship but is this ship so important to name the film? Nothing more important than this... "The Death Star" (for example) would be more clear and understandable name.

So far, is there any suggestion, or speculation as to the reason for the name 'Rogue One' for the next Star Wars film?   To me, the name seems very close to the Rogue Squadron, most known from Hoth (their leader Luke Skywalker), especially the number following Rogue like a callsign.   However as far as I know, they were formed after the first Death Star destruction. So why Rogue One?


Does static block of class execute before the main method of same class?   Example:  public class Example {      static     {         System.out.println("hi");     }      public static void main(String[] args) {          System.out.println("bye");      } }   The output of this program is :     hi      bye   My doubt is why the output was not:     bye

My question is about one particular usage of static keyword. It is possible to use static keyword to cover a code block within a class which does not belong to any function. For example following code compiles:  public class Test {     private static final int a;         static {         a = 5;         doSomething(a);     }     private static int doSomething(int x) {         return (x+5);     } }   If you remove the static keyword it complains because the variable a is final. However it is possible to remove both final and static keywords and make it compile.   It is confusing for me in both ways. How am I supposed to have a code section that does not belong to any method? How is it possible to invoke it? In general, what is the purpose of this usage? Or better, where can I find documentation about this?


The exercise is;     There are m functions from a one-element set to the set {1, 2, …, m}.   How many functions are there from a two-element set to {1, 2, …, m}?   From a three-element set? Give a recurrence for the number of T(n) of   functions from an n-element set to {1, 2, …, m}. Solve the recurrence.   I've gotten to the point that I "know" there are $m^n$ options to the function $$f:\{1,...,n\}\to \{1,...,m\}$$. How do I set up a recurrence relation and solve it?  I've gotten this far; $$ T(0) = 1 \\ T(1) = m \\ T(n) = T(n - 1) \cdot m $$  Solving it; $$ T(n) = (T(n - 2) \cdot m) \cdot m \\      = ((T(n - 3) \cdot m) \cdot m) \cdot m \\      = T(n - n) \cdot m^n \\      = 1 \cdot m^n = m^n $$  But I'm unsure whether I've even done the correct thing?

I've gotten stuck at the following exercise;     There are m functions from a one-element set to the set {1, 2, …, m}.   How many functions are there from a two-element set to {1, 2, …, m}?   From a three-element set? Give a recurrence for the number of T(n) of   functions from an n-element set to {1, 2, …, m}. Solve the recurrence.   I'm not sure how to begin solving it?


I'm trying make a clickable zone on a imageView in a fragment. I have the flowing error :  java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference  Does anybody can help me ? code of my fragment : RelativeLayout rl = (RelativeLayout) this.getView().findViewById(R.id.clikeable1);         rl.setOnClickListener(new View.OnClickListener(){             @Override             public void onClick(View v) {                 Toast.makeText(getActivity().getApplicationContext(), "toto", Toast.LENGTH_SHORT).show();             }         });  code of the relativelayout <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:layout_width="wrap_content"     android:layout_height="wrap_content">     xmlns:app="http://schemas.android.com/apk/res-auto"     xmlns:tools="http://schemas.android.com/tools"       <TextView          android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_alignParentStart="true"         android:layout_alignParentTop="true"         android:layout_marginStart="290dp"         android:layout_marginTop="110dp"         android:text="Entrez le code étape" />    <ImageView         android:id="@+id/imageView2"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         app:srcCompat="@drawable/password_keyboard" />      <ImageView         android:id="@+id/passwordKo"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_alignParentStart="true"         android:layout_alignParentTop="true"         android:layout_marginStart="295dp"         android:layout_marginTop="170dp"         app:srcCompat="@android:drawable/presence_invisible" />      <ImageView         android:id="@+id/passwordOk"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_alignParentStart="true"         android:layout_alignParentTop="true"         android:layout_marginStart="405dp"         android:layout_marginTop="170dp"         app:srcCompat="@android:drawable/presence_invisible" />      <EditText         android:id="@+id/passwordEtape"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_centerHorizontal="true"         android:layout_centerVertical="false"         android:layout_marginTop="35dp"         android:ems="3"         android:inputType="numberSigned"         android:maxLength="4" />       <RelativeLayout         android:layout_width="350dp"         android:layout_height="350dp"         android:id="@+id/clikeable1"         android:onClick="action1"         android:layout_alignLeft="@+id/imageView2"         android:layout_alignBottom="@+id/imageView2"/>  </RelativeLayout>  Thank you. Max

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I want to create my own Ubuntu distribution. I used cubic or a while, but i am not familiarized with it. I want to create my Ubuntu distribution in another way. For example create a restore point or a backup, or a sfs file of installed Ubuntu on my computer, and boot it on grub or any other bootloader. If not, by using Ubuntu Server or Ubuntu Minimal. Is it possible? Thanks!

I'm a new Linux user. I've reinstalled my Wubi from scratch at least ten times the last few weeks because while getting the system up and running (drivers, , etc.) I've broken something (X, grub, unknowns) and I can't get it back to work. Especially for a newbie like me, it's easier (and much faster) to just reinstall the whole shebang than try to troubleshoot several layers of failed "fixing" attempts. Coming from Windows, I expect that there is some "disk image" utility that I can run to make a snapshot of my Linux install (and of the boot partition!!) before I meddle with stuff. Then, after I've foobar'ed my machine, I would somehow restore my machine back to that working snapshot. What's the Linux equivalent of Windows disk imagers like  or ?  Note: I found a similar question:


key1 = value1 key2 =   value2 key3  =   value3   key value pair in one or more lines. Tried (\w+)\s{0,}=\s{0,}(("(.+?)")|(.+?)(?=\s|$))

Can someone provide a regular expression for parsing name/value pairs from a string?  The pairs are separated by commas, and the value can optionally be enclosed in quotes.  For example:  AssemblyName=foo.dll,ClassName="SomeClass",Parameters="Some,Parameters"


I installed Lubuntu on a flash drive as you would an HD (not live/squashfs). But whenever I boot it I get a grub rescue prompt.  It says it can't find /boot/grub/i386-pc/normal.mod which explains the rescue prompt. However, it's installed for x86_64. The folder for that arch is there with all the modules. When I did grub-install I targeted it to x86_64. When I try to explicitly insmod it it says wrong arch elf magic. So it is definitely looking for i386 and in the right place, but why and how do I fix it?  My question is different than the suggested duplicates because there is no Windows installation on the flash drive, which must be machine-independent. Also, the solutions provided in either do not help - even boot-repair doesn't fix it.

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


In old times we all were dealing with Arrays, then link lists came boasting the following:   it can grow and shrink at runtime by allocating and deallocating memory.   Insertion and Deletion. Insertion and deletion of nodes are  really easier. No Memory Wastage. Traversal. Reverse Traversing   While all above is true versus Arrays, I cannot find any benefit of a LinkedList over Generic List<T> ,as List<T> has all of the above properties.  Also, I have never seen LinkedList be used in any NET program.  I'm just looking to see if there is a situation which LinkedList<T> has an advantage over List<T>  ===============================================  Thank you all for your feedbacks! The link above proved to be very helpful.  Based on the above link and comments, at least in .NET world, LinkedList seems to be much inferior to LIST.


Provided this code  let myVar = 'hey' let myVar2 = myVar myVar = 'what'   When I assign let myVar2 = myVar, I am assigning a reference to myVar2? Or in the assignation myVar gets resolved and I am assigning the value that myVar has at that moment?  My doubt is whether    myVar2 holds a reference towards the original myVar (which is no longer available since it has been overwritten by the second assignation myVar = 'what') or myVar2 holds since the beginning whatever value had myVar, regardless that that variable will be overwritten later on

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


I am new to Linux & was running some random commands to experiment in terminal (Ubuntu-18.04 LTS) & by mistake I deleted my home directory.  The command I executed is shown in the screenshot of my history below. It was  rm -r /home/dawn   Now all my files are gone, as well as the default folders such as Pictures, Desktop, Screenshots, etc & my desktop screen has turned dark black.  When I tried to open the files icon, it's giving me an error.  Can anyone help me on this?

Are there any tools, methods, incantations to recover recently deleted files on Ubuntu?  If it makes any difference, I want to recover a  2.x database file. But would be better to have a method/tool that works on any kind of file.


I deleted the Ubuntu partition and started the Ubuntu installer up on a USB. The first time, I got the option to install alongside windows. However, I clicked an incorrect option and wanted to go back. I couldn't, so I restarted my computer. Now, I get the warning that UEFI mode could erase my other operating systems, but don't have the option to install Ubuntu alongside my other operating systems.


Yes, I know, in stars, fusion occurs up to Iron(-56); but, I want to know if fusion past this nucleus can happen at all.  If so, the daughter element would move to the right of the peak and its parents (away from the point of Iron-56), on the following graph (meaning additional energy is required, as opposed to energy being emitted), right?    Would fusion of heavy elements still be considered a reaction?  This is not a duplicate of . There are multiple questions, including the one about the graph, that are definitely not encountered in the other post. My main question is also different; the question and answers do not speak about fusion of heavy elements, but their rapid capture.  My question itself has nothing to do with stars, the first statements purpose was to dismiss comments telling me that stars only fuse up to Iron-56!

In all the discussions about how the heavy elements in the universe are forged in the guts of stars and especially during a star's death, I usually hear that once the star begins fusing lighter atoms to produce iron (Fe) that's the end of the star's life and the whole system collapses onto itself; and based on how massive the star was initially, it has different outcome - like a white dwarf, a neutron star or a black hole. I have rarely heard a detailed explanation of how the elements heavier than iron are produced. I would appreciate a convincing explanation of this process.


Yesterday Blender was working fine. Today it isn't recording any history, I can't undo anything. Also, when I add a new mesh, all the options in the Operator section of the Tool Shelf are grayed out, I can't do anything with them.   I checked User Preferences, it shows 32 steps in the Undo section of the Editing tab. I tried undoing by the Ctrl+Z shortcut, pressing the "Undo" button in the Tool Shelf, and clicking on the "Undo history" button, which does nothing. I tried closing Blender and opening it again. Rebooting does nothing. It was working fine yesterday. I have 2.76 running on Ubuntu 14.04 64-bit.   I need to go ask elsewhere how to check the most recent changes to my system - the system's software updater downloaded 40-odd MB of stuff this morning, but I don't know what it was.   Should this be reported as a bug?  Should I uninstall and reinstall Blender? When I open it, the mini-splash screen has a date and time in the top right corner - I'm guessing that indicates the last time the program was changed by an update. That date is a week ago, so that isn't it. Does that definitively mean the problem is with my OS?

Sometimes when adding an object to the scene I see that all options (on toolbar or in window after pressing F6) are disabled. Can anyone tell me when can this happen? What is causing it and how to revert it - make it enabled again. It worked for me when I restarted Blender and reloaded the scene. However I would really like to know what can cause it?


I am working on the curse of dimensionality (theoretical models) and would like to test an algorithm on it.  What I haven't found is a standard dataset that could be used to compare different approaches.    Is there such a thing?  Or... related: what is the most well-known failure due to the curse of dimensionality?

In the paper "" we read that,      We show that under certain broad conditions (in terms of data and query distributions, or workload), as dimensionality increases, the distance to the nearest neighbor approaches the distance to the farthest neighbor. In other words, the contrast in distances to different data points becomes nonexistent. The conditions we have identied in which this happens are much broader than the independent and identically distributed (IID) dimensions assumption that other work assumes.   My question is, how I should generate a dataset that produces this effect?   I have created three points each with 1000 dimensions with random numbers ranging from 0-255 for each dimension but points create different distances and do not reproduce what is mentioned above. It seems changing dimensions (e.g. 10 or 100 or 1000 dimensions) and ranges (e.g. [0,1]) do not change anything. I still get different distances which should not be any problem for e.g. clustering algorithms!   Edit: I have tried more samples, based on my experiments distances between points do not converge to any number, on the contrary the max and min distances between points get more apparent. This is also in contrary to what is written in the first post of  and also many other places which claim the same thing like . I would still appreciate it if someone can show me with a piece of code or real dataset that such effect exist in practical scenarios.


Hello guys, i'm very new in blender so can you help me please, i have no idea how to export this to unreal, because I still can't understand how the nodes system works,and what exactly this mesh is.  I created a skull, and want it to move in my game with smoke behind it, so i add a quick smoke and its absolutely works in Blender, but I don't know how to put it in FBX and should I create smoke in Unreal?  Is there a better and easier way ? In the end I want this skull  to move so it will make smoke behind.  Please if you can't give me an answer, a simple advise can be good too :)

I used node textures in a mesh I exported to .FBX.  I then imported it into Unreal Engine 4 and it didn't import any textures; I clicked the Upload Textures option in Unreal Engine.  Is there something I'm doing wrong or is it Blender?


I have a continuous outcome that I need to assume is right-censored, so I'm looking for a way to fit a tobit regression model, however, my data are from family pedigrees so I also have to account for non-independence of my observations in some way (say with a random effects term). Can anyone think of a way to achieve this in R?

Does anybody know where to find good application and examples (besides the manual and the book applied econometrics with R) using the tobit model with the packages AER? Edit I'm searching for a command to compute the marginal effects for y (not for the latent variable y*). It seems to be $\phi(x\beta/\sigma)\beta$, where $\phi$ is the std.normal cumulative distribution function. But how can I compute those effects with R?


I update my Toshiba PORTÉGÉ from Precise(12.04) to Quantal (12.10). After update to Precise wireless device works fine. But after update wireless device is not detect on network manager.  The lspci command says:  02:00.0 Network controller [0280]: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN      Controller [14e4:4727] (rev 01)             Subsystem: Askey Computer Corp. Device [144f:7175]             Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-             Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-             Latency: 0, Cache Line Size: 64 bytes             Interrupt: pin A routed to IRQ 3             Region 0: Memory at d4500000 (64-bit, non-prefetchable) [size=16K]             Capabilities: <access denied>             Kernel modules: bcma   The ethernet connection works fine. I try to install firmware-b43-installer but it says:  $ sudo apt-get install firmware-b43-installer ... Unsuported device(s) found: PCI id 14e4:4727 Aborting   More info related gived by lshw:      root@caprica:~# sudo lshw -class network   *-network                       descripción: Ethernet interface        producto: 82577LC Gigabit Network Connection        fabricante: Intel Corporation        id físico: 19        información del bus: pci@0000:00:19.0        nombre lógico: eth0        versión: 06        serie: e8:9d:87:ed:f4:2a        tamaño: 1Gbit/s        capacidad: 1Gbit/s        anchura: 32 bits        reloj: 33MHz        capacidades: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation        configuración: autonegotiation=on broadcast=yes driver=e1000e driverversion=2.0.0-k duplex=full firmware=0.12-6 ip=192.168.1.5 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s        recursos: irq:41 memoria:d4700000-d471ffff memoria:d472a000-d472afff ioport:3020(size=32)   *-network NO RECLAMADO        descripción: Network controller        producto: BCM4313 802.11b/g/n Wireless LAN Controller        fabricante: Broadcom Corporation        id físico: 0        información del bus: pci@0000:02:00.0        versión: 01        anchura: 64 bits        reloj: 33MHz        capacidades: pm msi pciexpress bus_master cap_list        configuración: latency=0        recursos: memoria:d4500000-d4503fff   I execute this too and this is the output:  root@caprica:~# rfkill list all 0: Toshiba Bluetooth: Bluetooth     Soft blocked: no     Hard blocked: no 1: hci0: Bluetooth     Soft blocked: no     Hard blocked: no   I have checking the model in :  BCM4313 - chipset uses unsupported LCN PHY, we work on it   I had configured privated drivers in the visual enviroment, Broadcom 802.11 Linux STA wireless driver source from bcmwl-kernel-source but don't work either.

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


is the fact of liberating an instance of a worksheet at the end of a procedure  useful for something? here's the code:  sub Macro(path as String)    Dim ws as worksheet   set ws = thisWorkbook.Sheets("Recap")   ....   ...'do actions on the sheet ws   ...   set ws = Nothing  end Sub   so my question is: if I do not release the object ws, is that it will automatically release?  Set ws = Nothing serves some at the end of the procedure?  thanks

I always read that it is recommended to set objects to nothing, once I am done with them. But I normally use them only in functions inside forms.  Isn't the reference lost and memory released when the function scope is left, regardless of setting objects to Nothing?   i.e. is it really necessary to do:  Set db = Nothing Set record_set = Nothing


What is the expected area of the intersection of a set of triangles made up N points that are picked uniformly inside a circle. The triangles must contain the origin of the circle? The expected area of one random triangle that contain a circle of radius R is given by : $ 4/(3 \Pi) R²$, see :

How to find the expected area of the intersection of a set of triangles made up $N$ random points that are picked uniformly inside a circle? The triangles must contain the origin of the circle. If none of the trinagles contain the rigin we pick again $N$ random points until at least one triangle contain the origin and calculate the expected intersection area of all the triangles that contain the origin.


class Date:     def __init__(self, digits):   #digits='10/20/21'         self.month = digits[:2]  #'10'         self.day = digits[3:5]   #'20'         self.year = digits[6:8]  #'21'      def __str__(self):         return f"Dated this {self.day} day of {self.month}, 20{self.year}"  def checkday(date):        #add 'st', 'nd', 'rd', or 'th' to day     if int(date.day) == 1 or int(date.day) == 21 or int(date.day) == 31:         date.day += 'st'     elif int(date.day) == 2 or int(date.day) == 22:         date.day += 'nd'     elif int(date.day) == 3 or int(date.day) == 23:         date.day += 'rd'     else:         date.day += 'th'  def checkmonth(date):     #get name of month     date.month = monthdic[date.month]  months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'June', 'Jul', 'Aug', 'Sep', 'Oct','Nov', 'Dec'] monthdic = {str(i): month for i, month in zip(range(1,13), months)}  date = Date(input("Enter date (mm/dd/yy):\t")) checkday(date) checkmonth(date)  print(date)  a couple of errors that come down to one problem that i did not think of: if it is january: 1/12/14 will not work because self.month is 1/12/14[:2]. Enter date (mm/dd/yy):  1/12/14 Traceback (most recent call last):   File "date.py", line 38, in <module>     checkday(date)   File "date.py", line 14, in checkday     if int(date.day) == 1 or int(date.day) == 21 or int(date.day) == 31: ValueError: invalid literal for int() with base 10: '2/'  if i resort to 01/12/14, this will also not work because 01 is '01' and monthdic['01'] does not exist: Enter date (mm/dd/yy):  01/12/14 Traceback (most recent call last):   File "date.py", line 39, in <module>     checkmonth(date)   File "date.py", line 28, in checkmonth     date.month = monthdic[date.month] KeyError: '01'  obviously def __init__(self, digits):     self.month = digits[:2]     self.day = digits[3:5]     self.year = digits[6:8]  is not the best approach, what are some good approaches (other than regex) ? also one thing: would it be appropriate to call checkdate() and checkmonth inside __init__?

I've got a huge list of date-times like this as strings:  Jun 1 2005  1:33PM Aug 28 1999 12:00AM   I'm going to be shoving these back into proper datetime fields in a database so I need to magic them into real datetime objects.   This is going through Django's ORM so I can't use SQL to do the conversion on insert.


How would I calculate something like 30! by hand? Is it necessarily tedious? Or are there some techniques to make it faster and easier?

I've been searching the internet for quite a while now to find anything useful that could help me to figure out how to calculate factorial of a certain number without using calculator but no luck whatsoever.  I'm well aware of the fact that there is a way to calculate any number of sigma (summation notation sigma) but haven't figured out anything for factorials yet. Could you please show me any method that should do the trick.  E.g. factorial of 10! is 3628800 but how do I calculate it without using any sorts of calculator or calculate the numbers from 10 to 1?  Thanks in advance!


I'm suffering from High Sierra, I need to downgrade but I can't find macOS Sierra dmg any where :| I have been searching for 2 days now but nothing, can anyone save me.

Sometimes it's hard to search for older versions of macOS & OS X  on the App Store.  This is an attempt to provide the canonical QA for this issue, as per the Meta QA -  I expect it to be modified over time to hopefully become a complete information resource.  How can I get any older version of a Mac OS to be able to run as a VM, or to reinstall on my Mac?


#include <iostream> #include <vector> #include <string> std::string likes(const std::vector<std::string> &names) { if (names.size() == 0) return "no one likes this"; else if (names.size() == 1) return names[0] + " likes this"; else if (names.size() == 2) return names[0] + " and " + names[1] + " like this"; else if (names.size() == 3) return names[0] + ", " + names[1] + " and " + names[2] + " like this"; else if(names.size() > 3) return names[0] + ", " + names[1] + " and " + (names.size()-2) + " others like this"; /*this line isn't working, i guess the problem is in names.size() */  The last line is causing my application to not run, i have tried every possible way i know to solve this but nothing really helped, can you please help?

I thought this would be really simple, but it's presenting some difficulties. If I have std::string name = "John"; int age = 21;  How do I combine them to get a single string "John21"?


In a previous post on this site, the question was asked, "Can we use two pronouns side by side?" However, the example given (and thus answers offered) didn't quite suit the particular question that I have.  Additionally, only the case of the specific example was addressed as opposed to the actual question in the title of the post.  In a sentence with an indirect and direct object, they should be separated by a preposition.  The girls gave Linda their keys.  They gave them to her.  (not)                                   They gave her them.  However, is that an absolute rule with possessive pronouns as well?   Linda didn't have her keys, so the girls gave theirs to her.  Would it also be correct to say:  Linda didn't have her keys, so the girls gave her theirs.  I'm not sure why in some cases, the two pronouns together "sound" OK, but in others they don't.  Linda didn't have a jacket, so I gave her mine. (Sounds OK to me)  Linda didn't have a jacket, so Tim gave her his. (Sounds questionable)  Even if these specific examples might be reworded for better clarity, the question is still whether or not, in any circumstances, object pronouns and possessive pronouns (which seem to also be acting as object pronouns here) may be used side by side.

Is it incorrect to say, 'Give me it' ?  I am told that it is and one should always say, 'Give it me'?


Did Nietzsche refer to the disease version of God (the fact that by the days of Nietzsche, Germans had found a cure for neurological Taenia Solium) or is he referring to the political definition of God (a king or an emperor).  In the later case, was he referring to the Chinese (opium war) or the French Bourbon (French Revolution).  The only war that is concomitant to Nietzche's statement are the Opim War or the fall of Napoleon III...  I am inclined to believe in the political version as the Germans had a cure for Taenia Solium long before the XIXth century, at least as a people...

What does German Philosopher Nietzsche mean when he says : "God is dead"? In one of the books of an Indian Mystic Osho, I read this reply from Osho: "Nietzsche is wrong because God has never been born". What is Nietzsche trying to imply from his statement?  Does Nietzsche also deny spirituality -- the idea of eternal soul, meditation, enlightenment (in the sense of Buddhism and Hinduism)? Some of your comments imply that he denies. But I have read a story (that sort of contradicts these implications, I think) about him in a book: One night he was found dancing on a street in Germany at night keeping a book on his head. Asked what he was really doing, he said: "I read many books in life. But throughout this long journey, I never encountered a book as beautiful as Geeta. After I read this book, I could not hide my happiness." As someone with some knowledge in Hinduism, I can tell that Geeta is perhaps the most important scripture in the religion.   I however have no references for this story as I read it long time back, and don't remember the book where I found it. If this really was a truth, Nietzsche certainly cannot deny spiritualism.


Is there a way to call a generic function in a foreach loop for Types known at compile time? This code wont compile, because type is not a valid parameter for DoSmth, but illustrates what I want to do.      public class X { }      public class Y { }      public class Z { }      public class Example     {         public Example()         {             Types = new List<Type>             {                 typeof(X),                 typeof(Y),                 typeof(Z)             };         }          private List<Type> Types { get; }          public void DoAllTypes()         {             foreach (var type in Types)             {                 DoSmth<type>();             }         }          private void DoSmth<T>()         {             // ... do smth based on T         }     }   Edit: Why is the question a duplicate? I specifically stated "known at compile time". The other uses Reflections to get the types not known at compile time.

What's the best way to call a generic method when the type parameter isn't known at compile time, but instead is obtained dynamically at runtime?  Consider the following sample code - inside the Example() method, what's the most concise way to invoke GenericMethod<T>() using the Type stored in the myType variable?  public class Sample {     public void Example(string typeName)     {         Type myType = FindType(typeName);          // What goes here to call GenericMethod<T>()?         GenericMethod<myType>(); // This doesn't work          // What changes to call StaticMethod<T>()?         Sample.StaticMethod<myType>(); // This also doesn't work     }      public void GenericMethod<T>()     {         // ...     }      public static void StaticMethod<T>()     {         //...     } }


Determine if the sequence $\{a\}_{n=1}^{\infty}$ defined by $$a_1>0\\a_{n+1} =\arctan{a_n}$$ is convergent and compute its limit.  Will Banachs Fixed Point theorem be of any help here?  My attempt.  We note that the recurrence relation is of the form $x_{n+1}=f(x_n),$ let's introduce the help function $f(x)=\arctan{x}.$ I know that the equation $f(x)=0$ has a root $x=0$, so I'll choose an interval $I=[0,\frac{1}{2}].$ In order to use the fixed point theorem, the following criterias have to be met:   $f(x)$ has to be defined and continuous on $I$ (OK!) $f(x)\in I$ for each $x\in I.$ (OK!) There should exist a $0\leq k<1$ such that $|f'(x)|\leq k<1.$   If all of these are met, it follows that $a_n$ converges to the unambiguous root of the equation $x=f(x)$.   The third criteria is where I run into problems. I get that  $$|f'(x)|=\frac{1}{1+x^2}\leq1,$$  So my $k$ is $1$, but I need it to be less than one! How can I go around this problem?

Here's my question:     Let $(a_{n})$ be a sequence where $(a_{1}) > 0$, defined as:   $$(a_{n+1})=\arctan*(a_{n})$$ for all $n$.   Prove that $a_{n}$ has a limit $L$ and calculate it.  Solution:   Prove that x>$arctan (x)$ for all x. Prove that above we can conclude that $a_{n+1}<a_{n}$, since they are equal we multiply $a_{n}$ by $arctan(x)$. $arctan(x)=0 \space iff \space x=0$, and that doesn't happen here since $a_{1}$ is positive. Therefore, we can use the follwoing theorem:      Let r be a number such that $r \in \Bbb R$ and $0<r<1$, so:   $$IF \space\space \left|\frac{a_{n+1}}{a_{n}}\right| \le r \Rightarrow \lim \limits_{n\to\infty}(a_{n})=0$$    Sorry for the last theorem - I don't know how it's named in English (I'm not a native speaker).  Is my solution correct?  Thanks,  Alan


How can i render a character + the shadow it cast on a surface but not the surface itself?  I would use it to    Render my background only once (if nothing moves in background) so i would be saving a lot of time  Better effects with transparency gif

I'm trying to make a logo that will be on the header of a website. What I'd like to achieve, and the reason I'm using Blender, is the projected shadows on the background looking perfectly real (as opposed to doing a drop-shadow in Photoshop).  The only thing is, the background has to be transparent because the website might use different background colors / gradients that make it impossible to match with the exported 3D background.  I made this dummy file (not the real logo... duh!):    If I use the file as is, the grey borders of the image will be impossible to match with the website's background color.  Here what I want:    So obviously, I tried masking the plane, which made the shadows disappear. I tried having a plane set to glass, which didn't work either.  And I looked around for a similar question, but didn't find one.   I am not trying to render , or a . I've seen  which has a very difficult solution to this problem, and  that is very similar but in Blender Internal.  is similar too but has never been solved. I'm only a beginner at Compositor, and I'm trying to learn more any chance I get, so any solution in Compositor is welcome if detailed enough. Although if there's a simpler or faster way, it's welcome too!  .blend file: