A few months ago I installed Windows 10 on my late 2013 iMac without any drivers. Stupidly, I deleted the OSX partition because the only thing that didn't work perfectly was audio, which I was fine with at the time.  I've recently started using Ubuntu on my iMac and audio is back to it's good ol' usual. However, I want to switch back to OSX so I can dual boot between OSX and Ubuntu. How can I reinstall OSX?  Thank you in advance.

I erased my Macintosh HD from Disk Utility with a journaled encrypted format and I wanted to install OS X 10.7 Lion. I left it to download and install overnight because it took about 16 hours.  When I checked it again it gave me a weird screen that has a circle with a slash inside it, like a stop sign. What can I do?


I want to group by a table by some columns and show values of other column.in SQL v.2017 I can do that with string_agg function. but my SQL version is 2012.How can I do that...  create table dbo.TaskPeriods (  [id] [int] NULL,  [startDate] [datetime] NULL,  [endDate] [datetime] NULL  )  ------------------------------- insert into test.dbo.TaskPeriods values(1,'2018-07-24 00:00:00.000','2018-07-24 10:00:00.000') insert into test.dbo.TaskPeriods values(2,'2018-07-24 00:00:00.000','2018-07-24 10:00:00.000') insert into test.dbo.TaskPeriods values(3,'2018-07-24 08:00:00.000','2018-07-24 12:00:00.000')  -------------------------------------------------------- select id,startDate,endDate from  test.dbo.TaskPeriods  -------------------------------------------------------- select  min (startDate) ,max (endDate) --,string_agg(id,',')  //How to Do this Without string_agg Function FROM test.dbo.TaskPeriods group by startDate,endDate

I'm trying to migrate a MySQL-based app over to Microsoft SQL Server 2005 (not by choice, but that's life).  In the original app, we used almost entirely ANSI-SQL compliant statements, with one significant exception -- we used MySQL's group_concat function fairly frequently.  group_concat, by the way, does this: given a table of, say, employee names and projects...  SELECT empName, projID FROM project_members;   returns:  ANDY   |  A100 ANDY   |  B391 ANDY   |  X010 TOM    |  A100 TOM    |  A510   ... and here's what you get with group_concat:  SELECT      empName, group_concat(projID SEPARATOR ' / ')  FROM      project_members  GROUP BY      empName;   returns:  ANDY   |  A100 / B391 / X010 TOM    |  A100 / A510   So what I'd like to know is: Is it possible to write, say, a user-defined function in SQL Server which emulates the functionality of group_concat?   I have almost no experience using UDFs, stored procedures, or anything like that, just straight-up SQL, so please err on the side of too much explanation :)


Show $$p< -\log(1-p)$$ for $0<p<1$. I thought about using Taylor expansion, is that the way to go?

Prove $\log(1+x) \lt x$ for $x\gt0$  my attempt:  I show $e^{x}\gt 1+x$ for $x\gt0$ since  $e^{x}=1+x+\frac{n(n-1)}{2}\frac{x^2}{n^2}+...$  so if $x\gt0$ then all terms are positive   so $e^{x}\gt 1+x$ for $x\gt0$  now given $e^{x}\gt 1+x$ for $x\gt0$, can I take $\log$ on both sides and show   $\log(1+x)\lt x$ for $x\gt0$  or do I have to prove firstly that $\exp(x)=e^x$ for $x\gt 0$ then I can take $\log$..


I need the following by the principle of Mathematical induction:  \begin{align*} 1 + \frac{1}{\sqrt{2}} + \frac{1}{\sqrt{3}} + \ldots + \frac{1}{\sqrt{n}} \leq 2\sqrt{n} \end{align*} I can easily find out the base case for n=1 is true.  However, I can't find the proof in the induction step.   I assume: \begin{align*} 1 + \frac{1}{\sqrt{2}} + \frac{1}{\sqrt{3}} + \cdots + \frac{1}{\sqrt{n}} \leq 2\sqrt{n} \end{align*}  To proof: \begin{align*} 1 + \frac{1}{\sqrt{2}} + \frac{1}{\sqrt{3}} + \ldots + \frac{1}{\sqrt{n}} + \frac{1}{\sqrt{n+1}} \leq 2\sqrt{n+1} \end{align*} Can someone help me find a way to proof the inductive step too?  Thank you!

Proving that the series 1 + ... + $1 / \sqrt{x}$ < $2 \sqrt{x}$  I am doing it by simple induction adding $1/\sqrt{x+1}$ to both sides, but I can't find a way to manipulate this expression and find that the new series is $< 2 \sqrt{x+1}$.  Can someone show me the correct process?  I failed many times and the furthest I've gotten has been to prove that it's $< 2 \sqrt{x+1} + 1$ which is close, but not enough.


Are there nonisomorphic, finitely generated groups that surject (homomorphically) onto each other? For example of the 'dual' problem, the free group on $2$ generators $F_2$, and the free group on $3$ generators $F_3$ inject into each other; but there is no surjection from $F_2 \to F_3$ (intuitively, if there was was, since $F_3$ surjects onto $\mathbb{Z}^3$, there would therefore be a surjection $F_2 \to \mathbb{Z}^3$, but the image of such a map could only be a $2$-dimensional sublattice of $\mathbb{Z}^3$, so we have a contradiction)

Let $G$ and $H$ be groups and assume that there exist onto homomorphisms $$\phi :G\rightarrow H,\qquad\psi :H\rightarrow G.$$ If $H$ and $G$ are finite then it is clear that $H$ and $G$ are isomorphic. It is also valid for finitly generated abelian groups. However, in general this is not true even in the abelian case.     My question is: if we know that $G,H$ are finitly generated and such $\phi ,\psi$ exist then are $G$ and $H$ isomorphic?


Needed some help with my Google Chrome, which randomly reverted to this pre-material design style. It happened a few weeks ago and have tried lots of methods to fix it but nothing worked. I also have adblocker installed, but somehow it still shows google ads etc.  It doesn't happen on Firefox.  I have tried reinstalling, changing chrome user, updated chrome to newest version, reinstalling adblock/different extensions, running incognito without extensions etc.  This image shows what it looks like now:  Google search on Chrome:    However, a normal google search should show something like this (it used to be like this):  Google search on Firefox:

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


Below is minimum code. If I compile by pdflatex, landscape worked. If I compile by lualatex, landscape didn't work. So, how to make landscape work with lualatex? Thank you.  \documentclass[a4paper]{article} \usepackage[margin=5.0mm,landscape]{geometry} \begin{document} \subsection[Dead load]{Dead load}  \end{document}

According to  (2010/09/12 v5.6, section 5.6 'Drivers', p. 11)     The package supports drivers dvips, dvipdfm, pdftex, xetex, and vtex.   Can I use this package with luatex? If so - which driver should I specify? If not - what are the alternatives?


I want to simulate some oil going from one tank 1 M^3 then down in a pipe and filling up a std 55 Gal barrel.  See image:    I've got several problems with this such as how to stop filling the barrel when it is full so it doesn't spill?  Also, if I use inflow it will overspill a lot! I could not get to do it with a very small pipe so is there a way to do it with a small pipe? Right now the pipe has a 1 foot diameter which is not realistic!  I can provide the file if needed.

I have fluid simulation with an inflow object. I want the inflow to go for 2 seconds, then have the inflow stop (so no more fluid is added) but keep the simulation going  (so the existing fluid sloshes around).  However, I do not see any way to set start and ending values on my inflow object.  How do I stop inflow at a certain frame/time in my simulation?


table1  a     b     c          1     2     3          1     2     5          2     3     4         ....   only combine rows with the same a and b: Desired result:  table2  a     b     c         1     2     3,5         2     3     4        ....   How? The real table contains like 15 fields, and want to combine rows base on 5 fields.


ANOTHER POSSIBLE DUPLICATE:        I'm new to optimizing pages for ranking in search engines and I've recently got in Google Search Console.  So whenever I try the URL Inspection tool with the home page of my site I get this message:     URL is not on Google       This page is not in the index, but not because of   an error. See the details below to learn why it wasn't indexed. Learn   more   Here's a more detailed view:   I'm feeling really frustrated because I don't really know what does this mean and there's no real actionable information on how to fix this.  However, when I try the Test Live URL feature I get the following:    This looks kind of ambigious information to me and I don't know if I should be worried?  I've tried to stick to the most fundamental practices for SEO so that everything on the page is moderately OK and does not have critical issues such as noindex etc.

This is a general, community wiki  question and answer pair intended to address any questions   concerning the reasons a site or specific site contents do not appear   in search engine results.      If your question was closed as a duplicate of this question and you   feel that the information provided here does not provide a sufficient   answer, please open a discussion on .   My site (or specific pages on my site) is not appearing in search engine results.  Why isn't my content indexed and what can I do about it?


Can I interchange while and when in the following sentences? 1- He waited while/when I combed my hair. 2- He was waiting while/when I was combing my hair.

What's the difference between "as", "when" and "while"?     The doorbell rang as/when/while Anna was asleep.   Which is right and why?


So in Java, you can do:  void F(int x, int y) {   run(x, y); }  void F(String a) {   say(a); }   but in Javascript you always have to do:  function F(x, y) {   if (typeof x == "string") {     say(a);   } else {     run(x, y)   } }   I want to do something like the Java functions in Javascript without checking every single thing, anyway to do that?

What is the best way(s) to fake function overloading in Javascript?   I know it is not possible to overload functions in Javascript as in other languages.  If I needed a function with two uses foo(x) and foo(x,y,z) which is the best / preferred way:   Using different names in the first place Using optional arguments like y = y || 'default' Using number of arguments Checking types of arguments Or how?


Setting up an array of (3) 5GB drives using btrfs.  It will soon grow to (6) 5GB drives.  Starting with raid 1, will rebalance once all the drives are installed to either raid5, 6, or 10.  I will be booting off of this, so I believe I need a bios_grub / BIOS boot partition.  How is this usually done?  I'm starting with:  # parted /dev/sda mklabel gpt mkpart grub ext3 1M 2M set 1 bios_grub on mkpart btrfs btrfs 2M 5001GB   I guess my preference would be that the BIOS boot partition be a raid 1 across all 3 (eventually 6), so there isn't just one drive hosting the boot partition that if it dies preventing booting before re-installing the boot partition to another drive.  mkfs.btrfs won't run on a 1MB partition.  Says the minimal size for each btrfs partition is around 16MB.  Syslinux can't boot off btrfs yet, so that's not an option.  (In this paragraph, using "boot" not in the sense of the bios_boot partition, bot the rest of the boot sequence.)  Would you increase sdX1 to 20MB, make a 20MB on each drive, and make a btrfs raid1?  (The 20MB doesn't matter at all with these sizes.)  Or, would you make a 1MB partition on each, make it ext3, and a mdadm raid1?  (Not even sure a mdadm raid can work for a bios_grub partition...)

I created a BIOS boot partition on a hard drive, using gdisk :  $ sudo gdisk /dev/sdb Command (? for help): p Disk /dev/sdb: 7821312 sectors, 3.7 GiB Logical sector size: 512 bytes Disk identifier (GUID): F7F2BE49-B8D8-4910-8E69-381DEBD954DC Partition table holds up to 128 entries First usable sector is 34, last usable sector is 7821278 Partitions will be aligned on 4-sector boundaries Total free space is 2 sectors (1024 bytes)  Number  Start (sector)    End (sector)  Size       Code  Name    1              36         7168035   3.4 GiB     EF02  BIOS boot partition    2         7168036         7821278   319.0 MiB   8300  Linux filesystem  Command (? for help): q   I need to mount this BIOS partition :  $ sudo mount /dev/sdb1 /mnt mount: block device /dev/sdb1 is write-protected, mounting read-only mount: you must specify the filesystem type   What is a relevant filesystem type to use in order to mount this BIOS partition? I read on the Internet that ext2 is fine, though I can't find an explanation why.


We all see that Craster's last son was turned into a White Walker, but still haven't seen any kid/infant White Walker or wight. It seems kinda weird, what will the White Walkers do with kids in their army? I don't think they can fight, so why turn them? We've seen that dead people become wights and they don't age, so do these babies grow old or something?

When Craster gives away the baby boys to the White Walkers, what happens? Do the baby boys become snacks at a White Walker party? Made into something else with magic?


Let $A$ be a $3\times 3$ matrix over $\mathbb {R}$ such that $AB =BA$ for all matrices $B$ over $\mathbb {R}$ then what can we say about such matrix $A$.  or such matrix $A$ must be orthogonal matrix? Can we say anything about its eigen values?  I tried by taking random examples also tried to construct such $3 \times 3$ matrices. But i am not able to get any proper conclusion and proof.

The question is from Axler's "Linear Algebra Done Right", which I'm using for self-study.  We are given a linear operator $T$ over a finite dimensional vector space $V$. We have to show that $T$ is a scalar multiple of the identity iff $\forall S \in {\cal L}(V), TS = ST$. Here, ${\cal L}(V)$ denotes the set of all linear operators over $V$.  One direction is easy to prove. If $T$ is a scalar multiple of the identity, then there exists a scalar $a$ such that $Tv = av$, $\forall v \in V$. Hence, given an arbitrary vector $w$, $$TS(w) = T(Sw) = a(Sw) = S(aw) = S(Tw) = ST(w)$$ where the third equality is possible because $S$ is a linear operator. Then, it follows that $TS = ST$, as required.  I am, however, at a loss as to how to tackle the other direction. I thought that a proof by contradiction,  ultimately constructing a linear operator $S$ for which $TS \neq ST$, might be the way to go, but haven't made much progress.   Thanks in advance!


What is the the most profitable way of transferring euro to usd in the states. First answer it by bank transfer. I guess there would be a lot of fees. Another way i guess is through bitcoin since it is universal but i do not know how safe this is and how you can transform money credit to bitcoins and vice versa. Recently i read about stellar network which provices transactions in multi-currency system through gateways that receive credit in a currency and transform it in a stellar.

I'm currently living overseas in Europe.  I work as a consultant for a US based company which pays me US dollars deposited to my US bank account.  It's getting to be pretty expensive when I withdraw money from the ATM (around $25 USD), or if I wire money from the US bank (Bank of America) to my account here ($45 USD).  Anyone have any suggestions on how to transfer money from my US account by paying less fees?  Any bank that has better deals, any services I can use, like online services?


Though the physical concepts and mathematics are highly rudimentary, I often try to comprehend exactly why light wants to keep it's frequency, yet alter it's wavelength as it travels through a medium, while at the same time, alter both it's wavelength and frequency while traveling through a vast series of gravitational fields.   My question is this:  If possible, try to address the situation without poking at the obvious holes in it.  Imagine that there exists a uniform $[2*2(ly^2)]$  body of fluid in the vacuum of space with an index of refraction $N$. Now imagine a massive wall of light enters this fluid (ignore any intensity fading/ dispersion), and doesn't exit to the other end for two years. Would the light wave exit the fluid with the same wavelength that it entered with? Why ?

When light passes from one medium to another its velocity and wavelength change. Why doesn't frequency change in this phenomenon?


so I have this list: a = [-11, 13, 13, 10, -11, 10, 9, -3, 6, -9, -6, -6, 13, 8, -11, -5, 6, -8, -12, 5, -9, -1, -5, 2, -2, 13, 14, -9, 7, -4]  and by using a set I need to remove the duplicates and also keep them in the same order  I used this code:  def unique(a):     a = set(a)     return list(a)   it does remove the duplicates when I use it but the problem is it returns them in numerical order like this:  >>> unique(a) [-2, 2, 5, 6, 7, 8, 9, 10, 13, 14, -12, -11, -9, -8, -6, -5, -4, -3, -1]   how can I return it in the same order as the original list while removing duplicates using sets?  EDIT:  so I've used this code because it worked:  def unique(a):     seen = set()     return [seen.add(x) or x for x in a if x not in seen]   but can someone explain to me what it does? because I need to make another once but it returns the list without negative numbers, and I can't do that unless I understand what that code does

Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:  def uniq(input):   output = []   for x in input:     if x not in output:       output.append(x)   return output   (Thanks to  for that .)  But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.  Related question:


In one of the movies, I remember that Ron Weasley is confused about Hermione very busy agenda, so it seems that there are several Hermione's, or she can time travel, or being in two places at the same time.  Which of the movies is that? How could she do that?

Since Hermione used the Time-Turner repeatedly during her third year, did she ever see her past self or other self accidentally when going to her classes?


Model: HP 15-af030ur inside Realtek RTL8723B *ware: 2 years have problems under Linux Ubuntu 14.04LTS -> 16.04LTS -> 17.04 Gnome 3.24 wayland Problem: weak wifi signal problem in ubuntu based linux distributions, but  work well with windows try all solutions, nothing help

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


Whenever I try to change settings for the Admin account or download any files/programs it asks for a password. I do not know/remember this password. I've tried resetting it and making a new account using ROOT, but it wont let me. when I try to change my password, this comes up. "Authentication token manipulation error". I would greatly appreciate some help in this matter.

I'm working on a Ubuntu system, and my client has completely forgotten his administrative password. He doesn't even remember entering one; however it is there.  I've tried the suggestions on the website, and I have been unsuccessful in deleting the password so that I can download applets required for running some files. Is there a solution?


Let $V$ be a vector space over $F$ with basis $\{v_1,\cdots, v_n\}$, and for every $i$, let  $f_{v_i}\colon V\rightarrow F$ be a linear map satisfying $f_{v_i}(v_j)=\delta_{ij}$. Then $\{f_{v_1}, \cdots, f_{v_n}\}$ forms a basis of the dual space $V^*$.   The map $T\colon v_i\mapsto f_{v_i}$ uniquely extends to a linear injective map from $V$ to $V^*$, and since these spaces have same dimension, $T$ is isomorphism. Thus $V$ and $V^*$ are isomorphic, when $dim(V)$ is finite. However there is a canonical isomorphism between $V$ and $V^{**}$ when $dim(V)$ is finite.  Question: Suppose that $dim(V)$ is finite. Then the above map $T$ is isomorphism which depends on choice of basis. But can we always say that there is no canonical isomorphism between $V$ and $V^*$?  My confusion lies here: I understood above discussion as:      if $dim(V)$ is finite, then there is isomorphism between  $V$ and $V^*$, which can be obtained by considering a basis of $V$ and corresponding basis of $V^*$. But, eventhough, this isomorphism $T$ depends on choice of basis, it may happen that there is another isomorphism $V\rightarrow V^*$, which is independent of choice of basis. How can I conclude that there is no canonical isomorphism between $V$ and $V^*$?

Question While looking over the exercise $3.F-34$ in Linear Algebra Done Right, I encountered the following paragraph  Suppose $V$ is finite dimensional. Then $V$ and $V'$ are isomorphic, but finding an isomorphism from $V$ onto $V'$, generally, requires choosing a basis of $V$. In contrast, the isomorphism from $V$ to $V''$ does not require a choice of basis and thus is considered more natural.  and these questions showed up in my mind: $1$. Does the word natural just means that we don't need to choose a basis? I have seen the word canonical is used in the similar manner too. Is there a more precise definition for natural or canonical? $2$. Assuming the answer to question $1$ is Yes, then why there is no natural isomorphism from $V$ onto $V'$? $3$. I think that there is a relation between the answer to question $2$ and the proof of Riesz representation theorem. So, if we cannot find a natural isomorphism between $V$ and $V'$ then it means that we cannot prove Riesz representation theorem without choosing a basis of $V$. Is this true?  Complementary Informations The Isomorphism from $V$ onto $V^{''}$. Suppose $V$ is a finite dimensional vector space. Consider the following map $$ \Lambda(v)(\phi)=\phi(v),  \qquad \forall v \in V, \,\, \forall \phi \in V^{'} $$ then $\Lambda$ is an isomorphism from $V$ onto $V''$. Riesz Representation Theorem. Suppose $V$ is a finite dimensional linear space equipped with an inner product and $\phi$ is a linear functional on $V$. Then there is a unique vector $v_0 \in V$ such that $$\phi(v) = {\langle v,v_0 \rangle}_{V}, \qquad \forall v \in V$$  Other Related Posts I found the following posts related to this question on MSE and MO. , , , .


I would like to document a directory structure, and installed tree to do so.  I don't wish to include files but only directories and symbolic links which point to directories (haven't decided if the symlinks should be recursive, and either way is fine).  There are some directories which I would like to include the directory name, but not any directories (or files) within it.  Looks like I need -d to only display directories.  I have been able successful exclude directories using -I somedirectory, however, not to exclude sub-directories such as -I somedirectory/somesubdirectory.  For instance, the intent of the below command is to display all directories and sub-directories within ~/some/base/directory/ except for sub-directories within ~/some/base/directory/myfirstdirectory/notthisone or ~/some/base/directory/myotherdirectory/oreventhisone (note that ~/some/base/directory/myfirstdirectory/notthisone, etc should be included but just not its sub-directories).  tree -d -I "myfirstdirectory/notthisone|myotherdirectory/oreventhisone" ~/some/base/directory   I've also tried escaping / or replacing it with a . wildcard.  How are given sub-directories excluded from tree's output?

I need to print the directory structure of our production system and I would like to remove some specific directories from the ?  How do we specify multiple ignore patterns for tree command?


I've been playing a board game called risk lately, and I'm very interested in the probability behind it. Sorry if this question is it the wrong category, but I assumed that it was largely statistical. Consider the following:  Suppose two people are playing a dice game involving troop exchanges called Risk. Each player (either attacker or defender) begins with a certain number of "troops" and rolls three dice. Depending on how many of one player's dice beats those of another (based on a special scoring system), each player can lose a fraction of their troops. A defending player has a 62% chance for a net win, while an attacking player has only a 37% chance. Specifically, a defending player has a 37.5% chance to take three of the attacking player's troops, while an attacking player has a 15.6% chance to do the opposite. There is a 25.5% chance that the attacking player will lose 2 troops while the defending one loses 1, and there is a 21.4% chance that the attacking player loses 1 troop while the defending player loses 2.  I've gotten this far, through a very long program, but I can't figure this out: How many troops should the attacking player have in comparison to the defending player to make it fair, or so that there should be 0 players left on both sides in theory?  Thanks!

I am playing Warlight online (something like Risk), and my goal is to create a bot which plays against other bots.  n=100 attacking troops will on average kill 60 (p=0.6) troops each turn,  n=100 defending troops will on average kill 70 (p=0.7) troops each turn. They attack exactly at the same time. Binomial distribution such that variance=n*p*(1-p)   My question is the following: imagine we have 40 troops and the enemy has 25 troops. I am interested in the case that I continuously attack. What would be the chance that I have won by turn X (e.g. X=5)?  For turn = 1, it is simply the cumulative sum from at least 25 kills:   $$\sum_{i=25}^{40} {40 \choose i} * 0.6^i * (1-0.6)^{(40-i)} = 0.440$$   I have played around with the binomial distribution, but I find it difficult to calculate because of this "in X turns"; it seems it really explodes the amount of calculations needed (by lack of a smart trick).  Can this be done analytically or am I best off just to simulate this (which I assume will be much slower)?  EDIT: Perhaps it can simply be done by using the 60% and 70%?


I would like to prove that if $T:X\rightarrow Y$ is a compact operator, then for every weak convergent sequence $(x_n)_{n\in\mathbb N}$ with $x_n\rightharpoonup x$ for some $x\in X$ it follows that $Tx_n\rightarrow Tx$ with respect to the norm on $Y$.  I started the proof with,  Since $(x_n)_{n\in\mathbb N}$ is weak convergent there exists a positive constan $C$ sucht that $||x_n||\leq C$ for all $n$. Hence by compactness it follows that $Tx_n$ contains a convergent subsequence i.e $Tx_{n_k}\rightarrow y$ for some $y\in Y$. Now it should be somehow possible to deduce that $y=Tx$. But I am not able to move on.   Could someone give me hint how to proceed? or even how to find a better start for my proof?  Thanks in advance!

I have a question. If $X$ and $Y$ are Banach spaces, we have to prove that a compact linear operator is completely continuous.  A mapping $T \colon X \to Y$ is called completely continuous, if it maps a weakly convergent sequence in $X$ to a strongly convergent sequence in $Y$ , i.e., $x_n\underset{n\to +\infty}\rightharpoonup x$  implies $\lVert Tx_n-  Tx\rVert_Y\to 0$.


I already known how to prove that $\lim_{x\rightarrow 0}x^{x^x}=0$ and $\lim_{x\rightarrow 0}x^x=1$. I also tried to use L'Hôpital's rule for this question but it didn't work. How to find the limit? (The limit should be $1$ from the graph sketching.)

I'm a computer student, learning math just for fun. Today I was  that I found something strange! I noticed that that wired function ${x^{x^{\cdot^{\cdot^{x}}}}}$ in zero, seems to converge to 1 when there are even powers and to 0 when there are odd powers! Then I attempt to prove it but I failed.  Then I did a little research and I found the  article on Wikipedia. This article says that my guess was right but without any proof. So I'm here to ask you about it.     If we define ${x^{x^{\cdot^{\cdot^{x}}}}}$ as ${^{n}x} :=\begin{cases} 1 &\text{if }n=0 \\ x^{\left(^{(n-1)}x\right)} &\text{if }n>0 \end{cases}$      then prove:      $$\lim_{x\rightarrow0} {}^{n}x = \begin{cases}   1, & n \text{ even} \\  0, & n \text{ odd} \end{cases}$$


There has been a similar question back in 2015 which was answered here:   However time has passed and those scripts no longer seem to be working.  Here's what I'm trying to achieve. I have a scene in Blender with a large amount of tree objects. I want to introduce a few more types of trees into the mix by selecting some of the existing trees and replacing them with Ctrl+L > Link object data. However, because of the irregularity of the terrain they sit on and the difference in scale of these trees, the only reliable way to make sure I dont get floating or sunk trees after replacing is to have the very base of each tree as its origin. Scale after replacement is irrelevant, I can randomize it and it looks good enough.  I'm asking for either a script that can do the above or new ideas on how I could go about replacing these objects. Thank you in advance.

I have a lot of 3D objects of various sizes, shapes in blender 2.76b and I would like to set the origin to the bottom center of the objects bounds.  I cannot select the bottom edge and snap to cursor etc as each shapes edges are in different X/Y positions.  Is there a script or tool that will allow me to set the origin to the lowest edge z position?


I have a 13" MacBook Pro, mid 2012, in which I installed a Crucial 1TB SSD, and installed macOS Sierra, then upgraded to High Sierra.  Recently it would not boot after waking up from sleep, then I had to restart.  For 2 times it showed up the forbidden sign. In those situations I turned off and on again and everything worked just fine.  Last time it happened I was not successful, so I tried:   reset NVRAM, holding CommandOptionPRtogether, on statup; reset SMC, holding left ShiftControl Option together, with laptop switched off then turning it on; reset SMC, holding power button for 8sec while turning it on; go to recovery mode ans reinstall macOS High Sierra from USB drive go to recovery mode, format disk, even erasing partition, and creating new ones, then installing High Sierra, go to recovery mode, tried the same as previous fix, but installing macOS Mountain Lion, from local/ROM (I guess?) drive - not from DVD or any wired connect disk.   While booting, system still flashes "Apple logo", "forbidden sign" and "folder with ?", by this same order, sequentially, quickly.  Nothing worked so far. Tried system diagnostics from Apple (turn on + press D), performing exhaustive test, and it is passing all tests.  Does anyone have any clue? Appreciate all the help!

I currently own a 15 inch MacBook Pro with retina display model ( early 2013) . My Mac was working fine and all of a sudden my Mac won't boot up. I see a flashing folder with a question mark symbol on my screen.  I took my Mac to a technician who diagnosed the issue and said flash disk has to be replaced. He said  "Reseted SMC and PRAM. Still same issue. Tried to erase the SSD by booting with known good OS. still same issue. tried to erase the SSD using terminal mode same issue. tried to repair the SSD found not getting repaired. Reseated the SSD and tried to erase the SSD still not able to erase the SSD".  Is there any other way to fix this issue without replacing the SSD?   Or could you suggest any other SSD for this model of Mac?


I would like to redirect the default wordpress password reset url /end-point. So the url before the password is reset.  /wp-login.php?action=lostpassword  redirect to /password-reset/ (which is aalready setup)  I have created a custom page, so any user querying the old url will be redirected to the new page.

I used iThemes Security (formerly Better WP Security) hide back-end functionality to change the login url to /signin however clicking the lost password link /wp-login.php?action=lostpassword now generate a 404  Manually going to /signin?action=lostpassword works.  I came across the following code below which is suppose to make the change to however after some testing it doesn't seem to work  //******************************************************* //Function to change to lost password url //******************************************************** add_filter('site_url',  'wplogin_filter', 10, 3); function wplogin_filter( $url, $path, $orig_scheme ){     $old  = array( "/(wp-login\.php)/");     $new  = array( "signin/"); //this can be change to login or whatever or may remain there     return preg_replace( $old, $new, $url, 1); }   add to .htaccess  RewriteRule ^signin$ wp-login.php   How can i modify the above code in order to change the url for the lost password?


I have noticed a strange behaviour when switching between the packages german and babel with the german option. There is obviously a difference in how "= is handled in the preamble:  \documentclass{article} \usepackage{german} \title{Some"=Thing} \begin{document} \maketitle  Some"=Text. \end{document}   yields the following result:    while the following code  \documentclass{article} \usepackage[german]{babel} \title{Some"=Thing} \begin{document} \maketitle  Some"=Text. \end{document}   does not handle the "= in the \title{} command correctly:    What is the reason for this behaviour? How can I make the babel package behave like the german package? (I have to switch from german to babel because some packages like fancyref use the wrong translations if only german is used.)

The package babel with the ngerman option (and most other languages as well, but not english) provides the shorthand "|, which prevents a ligature at the given position (see p. 81 of the , e.g. Auf"|lage will result in the word Auflage without an fl-ligature (as is desired because, in German, you don't want ligatures across morpheme borders).  However, when placed in a macro, "| doesn't work anymore. Why is this and how can I circumvent it?  \documentclass{article}  %\usepackage[T1]{fontenc}% doesn't help \usepackage[ngerman]{babel}  \newcommand{\foo}{"|}  \begin{document}  ff  f"|f  f\foo f  \end{document}


I've got a broken power supply for charging a lithium-ion battery with the following specifications: INPUT: 220-240VAC~50Hz MAX 11W OUTPUT: 4.2VDC 1200mA  As I'd like a new power supply and I don't find one on, e.g. amazon, my question is in what way do I have freedom in specifications of a new power supply?  What I found so far are specifications of switching power supplies like this:  INPUT: 100-240 Volt AC, 50/60 Hertz OUTPUT: 3 / 4,5 / 5 / 6 / 7,5 / 9 / 12 VDC - 600 mA  INPUT: 110V-240V AC OUTPUT: 3V / 4,5V / 5V / 6V / 7,5V / 9V / 12VDC 600mA at 3V-6V / 450mA at 7,5V / 400mA at 9V / 300mA at 12V  INPUT: 100-240 V AC OUTPUT: 3-12 V DC (3,0/4,5/5,0/6,0/7,5/9,0/12,0 V) 1000mA  INPUT: 100 ~ 240V 50/60HZ, max. 500mA OUTPUT: 5V/2,4A; 6V/2A; 7,5V/2A; 9V/2A; 10V/2A; 12V/1,5A; 15V/1,5A   Is one of these four power supplies eligible as a replacement?

Power supplies are available in a wide range of voltage and current ratings.  If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to specify?  What if I don't know the device's specs, but am replacing a previous power supply with particular ratings?  Is it OK to go lower voltage, or should it always be higher?  What about current?  I don't want a 10 A supply to damage my 1 A device.


Will the C++ compiler, VS2010, convert big-endian to little-endian data for use on x86 machines?

How do I convert between big-endian and little-endian values in C++? For clarity, I have to translate binary data (double-precision floating point values and 32-bit and 64-bit integers) from one CPU architecture to another.  This doesn't involve networking, so ntoh() and similar functions won't work here.  Note: The answer I accepted applies directly to compilers I'm targeting (which is why I chose it).  However, there are other very good, more portable answers here.


I'm typing a minutes of meeting and the spell check doesn't recognized spelling error inside the table. I'm using office 365, word 2013.

Microsoft Word doesn't even recognize misspelled words when I have "check spelling as you type" boxed checks in the proofing options.  I've even purposely misspelled words inside tables and they don't show as misspelled.


Let's assume I use a broker like Ameritrade or Schwab etc. to buy Mutual funds, ETFs, stocks etc.  Now, let's assume that some point down the line the broker company goes bankrupt or shuts down due to other reasons.   What exactly happens to my investments. I assume those are safe (or not entirely?! eeks!)? But how do the instruments get transferred to a new broker etc.   In other words, how portable are my investments? Are there significant transfer costs?   Just like there's federal deposit insurance is there any equivalent for brokerage firms? In today's world where most of the data is stored in electronic format how would I even access the details of my portfolio if my broker suddenly shut down?  Are there any similar cases or precedent?  Note: I am not talking about the stock target itself going bankrupt. Just the broker going bankrupt.  i.e. Also NOT seeking protection against market influenced value decline. That I understand.  To rephrase: To what extent is a broker failure affecting me? e.g. Say I use a broker to buy a house or a car via a broker. Then the broker bankruptcy hardly affects my asset. What I want to know is how similar or different is this situation when it comes to investments?

I've noticed (for awhile now) that my online discount brokerage account carries many features of a traditional bank account:   Online bill pay Direct Deposit Checks ATM Card FDIC or SIPC coverage Cash transfers to/from external accounts   Considering this type of account also offers an insane selection of short and long term investment options, I'm wondering what are the cons to using this account for day to day banking.


I drive a Scion XD, and I've noticed that whenever I drive at about 40mi/hr or so with just the back windows rolled down, I get a loud "booming" effect at roughly 10Hz. What causes this? I assume it has something to do with air pressure "bouncing" back and forth in the car.  I can try to sketch the interior, if needed.

When you're driving and you open 1 car window, say the front one, there comes a horrible noise, but when you open another window just the slightest bit, this noise goes away (I'm sure most people know what I'm talking about then I mention this 'noise').   Why does this noise occur? Why does it go away when another window is slightly opened?   (Not sure about the tag).


Does the Sum from N=1 to N=∞ of : (-1^(N+1))((1/P(N)), where P(N) is the nth prime number, converge? If so, to what number does it converge?  Or in different terms, does the sum of the reciprocal of primes, where there are alternating signs, converge?  Example: (1/2)-(1/3)+(1/5)-(1/7)+(1/11) . . . = ?

$$\sum_{n = 1}^\infty \frac{(-1)^n}{p_n}$$ where $p_n$ is the $n$th prime.  I have computed this to 10000 rather than infinity. My results suggest that convergence does happen but it's very slow. But I can't even be sure about the first few digits: $-0.26959$?  I have looked at the "questions that may already have your answer" and some of the "similar questions," but they involve somewhat different formulas.


i am currently using <a href="somelink.com"><a/> and on click the href the href and Dom event both are called i need only DOM event to be called href should be only used for opening link in new tab

I have some HTML and jQuery that slides a div up and down to show or hide` it when a link is clicked:

     YOU CLICK THIS TO SHOW/HIDE

CONTENT TO SHOW/HIDE

   $('div.toggle').hide(); $('ul.product-info li a').click(function(event){   $(this).next('div').slideToggle(200); }   My question is: How do I use preventDefault() to stop the link acting as a link and adding "#" to the end of my URL & jumping to the top of the page?  I can't figure out the right syntax, I just keep getting an error saying      preventDefault() is not a function.


In part one of the Battle of Geonosis in season 3 of Star Wars Rebels, Ezra and Kanan are confronted by a destroyer droid with a shield in a narrow corridor. They draw their lightsabers to defend themselves, but it seems like it would have made sense to force push the droid back up the passageway to attempt to create space and distract the rest of the droids behind. They certainly have no problems force pushing normal battle droids. I recall similar scenarios in the clone wars but haven't watched that in a while so I can't provide specific examples.  This got me wondering, is there any canon evidence of technology (such as the destoryer's shields) protecting against force powers (such as force push) that goes above and beyond 'normal' limitations of the force (e.g distance, size)?

I haven't seen it in movies & TV shows (And, no luck regarding novels as I haven't read any). But, in many Star Wars video games, I experience disturbance while using force in some tech environment. Is there any canonical explanation of it? I don't consider video games under canon..


I have a bash script that has permission to execute, but when I double click it in nautilus it won't execute, instead it opens as text in gedit.   In properties it says open with: gedit, and that doesn't change when I click the reset button.  What do I have to do to make it execute? I'm running Ubuntu 13.04. I never had an issue like this one with 12.04 or with any other distribution in general.  EDIT If I go in terminal and type: ./bashscriptname it runs just fine.

When I double-click on a script in Nautilus to run it, the script just opens in my text editor with no option to run it. Using Nautilus, how do I run executable text files and/or scripts?


What do I need to look for in order to tell if a  relation on a set is a function?  Can somebody provide some advice?  For example, the relation is defined by $H$ on $A \times \mathcal P(A)$ for $a ∈ A$ and $B ⊆ A$, $a\, R\, B$ iff $a ∈ B$.  Where $A =\{0,1\}$ does this mean H is a function?

Assume you have an arbitrary set A, let RA be the relation defined on A × Power Set(A) by, for all a ∈ A and B ⊆ A,  "a RA B iff a ∈ B"  1.Let A = {0, 1}. Is RA a function? Justify?  2.Find a set A such that RA is a function.  does anybody have an idea of what to do? Im confused on trying to show its a function  The powerset(A) = {{0},{1},{EmptySet},{0,1}}   is RA a function then? because the X value is connected to a Y value?


Is there any way of simplifying or expanding the following expression:  $\lfloor ab\rfloor$  where $a$ and $b \in \mathbb{R}$? I know there exist formulae that allow simplifying the floor of a sum, or the floor of a quotient of two integers, but none that invlove the floor of a product. If simplifying is not possible, is there a way to expand it so that $a$ and $b$ are not "grouped" together within the floor function? Something like $\lfloor ab\rfloor = \lfloor a\rfloor \lfloor b\rfloor +...$

Is there any way the following can be simplified?  $$\lfloor f(x)\cdot g(x) \rfloor - \lfloor f(x) \rfloor  \cdot \lfloor g(x) \rfloor$$


I've installed the small image of Debian Wheezy from  but had to skip the mirror install of the extra packages.  Now that I have the command line how do I get the rest of the stuff?  When I tried apt-get install ssh-server, it told me to insert the CD.

I've just installed Debian 6.0.4 on VirtualBox, and I'm trying to install g++. So, into the terminal I typed:  aptitude install build-essential   But it's trying to get the package from disk:  Media Change: Please insert the disc labeled 'Debian GNU/Linux 6.0.4 _Squeeze_ - Official i386 CD Binary-1 20120128-12:53' in the drive '/media/cdrom/' and press [Enter].   Why isn't it just downloading it from Debian's repositories? Can I change this behavior?


Page 31.     Corollary 1.5.  Let $k$ be a field, and let $S = k[x_1, \dots, x_r]$ be a polynomial graded by degree. Let $R$ be a $k$-subalgebra of $S$.  If $R$ is a summand of $S$, in the sense that there is a map of $R$-modules $\varphi: S \to R$ that preserves degrees and takes each element of $R$ to itself, then $R$ is a finitely generated $k$-algebra.      Proof. Let $\hat{m} \subset R$ be the ideal generated by the homogeneous elements of $R$ of strictly positive degree.  Since $S$ is Noetherian, the ideal $\hat{m}S$ has a finite set of generators, which may be chosen to be homogeneous elements $f_1, \dots, f_s$ of $\hat{m}$.  We shall show that these elements generate $R$ as a $k$-algebra.   Why is the bolded part true?

Let $R$ be a $k$-subalgebra of $S=k[x_1,x_2,\dots,x_n]$. Let $m\subseteq R$ be the ideal generated by the homogeneous elements of $R$ of positive degree. As $S$ is Noetherian, the ideal $mS$ has a finite set of generators, which may be chosen to be homogeneous elements of $m$.    Why can we choose homogeneous elements of $m$ to be the generators?


If $G$ be a finite group such that $3$ does not divide the order of  $G$.   Then show that every element of $G$ can be expressed as $h^3$ , for some $h \in G$.   Thought:  I have just figured out that if $g$ has order $3$ then $g= h^3$ is not possible. But nothing else.

Let $a$ belong to a group and $|a|=m$. If $n$ is relatively prime to $m$ show that $a$ can be written as the $n^{th}$ power of some element in the group.   We need to show that if $a\in G$ and  $a^m=e\implies \exists \ b\in G $ such that $b^n=a$ i.e.$b^{nm}=e=({b^m})^n$ i.e. $\exists$ an element of order $mn$ in $G$.   How to show this?


I have an Activity which implements two interfaces for call backs on certain actions. I want to send a context of my Activity to another Class which will access the object of the specified callback.  Here is my code :-       public class OpenSchoolFragment extends Fragment implements IOpenSchoolCallBack, INetworkCallback     { // 1st case        expandableListAdapter = new AdapterOpenSchool(getActivity(), this); // IOpenSchoolCallBack should provided  //2nd case call.enqueue(new Callback<OpenSchool>()         {             @Override             public void onResponse(Call<OpenSchool> call, Response<OpenSchool> response)             {                  if (response.isSuccessful())                 {                     OpenSchool userBatch = response.body();                     if (userBatch != null)                     {                         RLProgressRoot.setVisibility(View.GONE);                     }                 }                 else                 {                     RLProgressRoot.setVisibility(View.GONE);                     if (response.code() == getResources().getInteger(R.integer.integer_404))                     {                         DialogHelperUtil.showRetrySnackbar(RLContainer, getString(R.string.str_error_unauthorised),this); //INetworkCallBack should be provided                      }                     else                     {                         DialogHelperUtil.showMessageSnackbar(RLContainer, response.raw().message());                     }                 }             }          }   So when I try to pass "this" in the second case, I get an error saying :-  Wrong 3rd argument type. Found: 'Callback<OpenSchool>', required: 'INetworkCallback'   How can I make sure the right callback is passed in "this" for the second case ie. INetworkCallback?

In the following snippet:  public class a {     public void otherMethod(){}     public void doStuff(String str, InnerClass b){}     public void method(a){         doStuff("asd",             new InnerClass(){                 public void innerMethod(){                     otherMethod();                 }             }         );     } }   Is there a keyword to refer to the outer class from the inner class?  Basically what I want to do is outer.otherMethod(), or something of the like, but can't seem to find anything.


I have read in some distant future predictions that after some years(numbers like 101500 years) random quantum fluctuations could produce a new Big Bang.  Is that possible, and is it possible now, or certain conditions must be met?  Many sources also state that after that much time there will be only subatomic particles left in the Universe, and if a new Big Bang doesn't happen it will end in heat death scenario(permanent end)?

Some say we live in the golden age of the universe because there exits countless number of stars that shines in the dark universe. As the supply of gas for star formation is steadily being exhausted, it is estimated that star formation will cease in 100 trillion years.  Question: Will there be a day that the universe becomes completly dark when all the stars burn out? Does all the cooled bodies eventually collide due to gravitational forces? Will black holes eventually dominate the universe?


I was wondering if the hats that I gained during this period will remain or I have them only during Christmas.  If it has an end, when does Winter Bash and hats period ends?

I really like how, in the winter bash, there are hats. They are pretty cool and actually encourage me to get badges, something I didn't care about before. I think there should be something like this, but all year round, to encourage people to get badges. Badges, to me, seem currently pretty useless and I never want to get any because...there is no good reason to. Hats: well, hats are just awesome


In Google,   While searching my (Magento) site, the meta title appears twice.  I am new to Magento, and don't know why it's appearing twice.

Does anyone know why Google shows my title twice in search results? And it's the wrong title too.  Here's a screenshot:


I have a form where I want the user to input a few fields and the form will calculate the total and percentage of goal. I'm new to JavaScript, and I don't know how to calculate a percentage. When I try parseInt(total)/parseInt(goal)*100 I get a NaN error:  <html>    <head>      <style media="screen">         .testform INPUT {             display: block;             margin-bottom: 10px;             border: 1px solid #212121;             height: 35px;             font-size: 16px;         }      </style>      <script type="text/javascript">         calculate = function() {             var cash = document.getElementById('a1').value;             var checks = document.getElementById('a2').value;             var coin = document.getElementById('a3').value;             var goal = document.getElementById('goalamount').value;             var total = document.getElementById('a4').value;              document.getElementById('a4').value = parseInt(cash)+parseInt(checks)+parseInt(coin);             document.getElementById('a5').value = parseInt(total)+parseInt(goal);         }     </script>   </head>   <body>     <form class="testform">       Goal amount <input id="goalamount" type="text" value="3000"/>       Cash Collected <input id="a1" type="text" />       Checks Collected <input id="a2" type="text" />       Coins Collected <input id="a3" type="text"  />       Total Collected <input id="a4" type="text" name="total_amt" onblur="calculate()" />       Percent of Goal<input id="a5" type="text" name="goal_amt" />     </form>   </body> </html>

What's the difference between JavaScript and Java?


I have a python script, and i'd like to make it run every 10 minutes, how can i do this? Thanks in advance.

I want to schedule a task to run on a regular basis and have heard that Cron is the way to do this.  How do I add Cron jobs in Ubuntu?


I have a function which is supposed to work with given ArrayList<String> and return the output as ArrayList<Integer>. The problem is NullPointerException is raised on hourList.add(hourInt); and I don't know why.  public ArrayList<Integer> takeTime(ArrayList<String> logs)  {      ArrayList<Integer> hourList=null;     Integer hourInt;      for(String line: logs) {          String[] matrix = line.split(" ");              String[] hour = matrix[3].split(":");         //  System.out.print(hour[0]+"\n");         String s = hour[0].replaceFirst("^0+(?!$)", "");          hourInt = Integer.parseInt(s);        System.out.print(hourInt+",");          hourList.add(hourInt);   // <--- NullPointerException here     }   return hourList;   }   System.out.print(hourInt+",");:     0,0,0,0,1,1,2,3,4,4,4,4,4,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10

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 have a problem when I run command sudo apt update it doesn't work:  E: Type 'gpg' is not known on line 1 in source list /etc/apt/sources.list.d/brave-browser-release.list E: The list of sources could not be read.

Every once in a while I see users having issues to update due to errors like this:  E:Type 'ain' is not known on line 1 in source list /etc/apt/sources.list.d/some-ppa.list'   with varying types/line numbers/source list files (often after removing a PPA).  How can such an error be fixed?


I was going through my old code and I stumbled upon some strange behaviour.  Folder and files inside it are chowned to me, however I am not allowed to enter it, or even list its content. Unless ofcource I am a root user.  Here is a screenshot. Could you please explain ?   GNU coreutils : 8.25, OS : Ubuntu 16.04.2 LTS

In my CMS, I noticed that directories need the executable bit (+x) set for the user to open them. Why is the execute permission required to read a directory, and how do directory permissions in Linux work?


Can anybody tell me what is happening in this assignment statement? It was found in some code in a textbook.  Somehow this is where val is initialized and without it it does not compile.  INT_MAX is coming from  The body of the code shouldn't matter too much but I've never seens two values to the right of an assignment operator int lru = INT_MAX, val;   Edit: People need to relax. This is getting downvotes WAY after it was answered. (I lost my ability to upvote which was not cool) I had an honest question that my TA nor my professor could answer. Thats because normally people write int val int lru = INT_MAX  on separate lines. Or they define them both as ints int val, lru and then assign lru = INT_MAX And at the very least put all the assignments/constructions after the definitions int val, lru = INT_MAX It was an honest question. I did research, I looked through previous questions and answers and couldn't find what I was looking for.

How does the comma operator work in C++?  For instance, if I do:  a = b, c;     Does a end up equaling b or c?   (Yes, I know this is easy to test - just documenting on here for someone to find the answer quickly.)  Update:  This question has exposed a nuance when using the comma operator.  Just to document this:  a = b, c;    // a is set to the value of b!  a = (b, c);  // a is set to the value of c!   This question was actually inspired by a typo in code.  What was intended to be  a = b; c = d;   Turned into  a = b,    //  <-  Note comma typo! c = d;


is there a way to write everything, even math symbols, in normal font? I know you can write text in \text{Normal font}, but I dont know how to do the same with math symbols.  \documentclass{article} \usepackage{amsmath}         \usepackage{amssymb}  \begin{document} $\text{Give me normal font}\, and \,not \,this\, one\, please\,  x \in \mathbb{Z}$ \end{document}

I read many things about people wanting math mode in sans-serif font and doing crazy things with packages and options to get that, but I did not find anything that would simply make my math mode font non-italic.  Is there an (easy) way to set math mode font to be non-italic?  And is there a way to do that globally for the whole document?


I was trying and could not, as it shows that $$8\mid n(n^{2}-1)(3n+2);\forall n \in \text{N}$$ Induction; looking eight consecutive numbers, what to do and how to do?$$$$Sorry, forgot to add a detail: I understand the statement without using modular arithmetic (content not yet studied).

"Prove that for every $ n $ natural, $24\mid n(n^2-1)(3n+2)$"  Resolution: $$24\mid n(n^2-1)(3n+2)$$if$$3\cdot8\mid n(n^2-1)(3n+2)$$since$$n(n^2-1)(3n+2)=(n-1)n(n+1)(3n+2)\Rightarrow3\mid n(n^{2}-1)(3n+2)$$and$$8\mid n(n^{2}-1)(3n+2)?$$$$$$ Would not, ever succeeded without the help of everyone that this will post tips, ideas, etc., etc.. Thank you.


Is there a way either built-in (don't think there is) or via a third-party to specify the volume on a per application basis in Windows XP? For example, right now I am listening to some music on fairly loudly and I would like all of the alerts I am getting from other apps (email, twitter updates, IMs) to be reduced.

Is there any way to individually control each program's sound volume in Windows XP? It'd be better if it was built-in instead of an app, but whatever works.


So I'm trying to find $9^{65}\pmod{77}$. What I've done: I used Fermat's little theorem and separated them into $9^{65}\pmod7$ and $9^{65}\pmod{11}$, where I got the remainders to be $4$ and $1$ respectively. Now, I have no idea what to do from this point. What is the best way to combine both to get the final answer?

How do I get the solution given by CRT to match another solution, e.g. the least positive? For example say I have X = 1234. I choose mi as 5, 7, 11, 13. This satisfies the simple requirements of . More precisely given in my example k = n = 4, and the product of any k - 1 is smaller then X how come simply computing the remainder of each won't give equations that solve to X = 1234. In the case of the example, x = 4 mod 5 x = 2 mod 7 x = 2 mod 11 x = 12 mod 13  Which resolves to  (won't CRT produce the smallest?) Any hints?  Below is the solution linked to on "Math Celebrity" (cached to avoid link rot).


I'm interested in seeing which tag is responsible for marking a question as 'interesting'. A slight change to its visual representation would be enough.

Each of us have our list of favorite tags.  When a question has tag(s) that match one or more of ours, the background gets highlighted, drawing our attention to the question.  It would also be nice to highlight (perhaps using a bold font) the tags(s) that matched our own, so one could quickly do a further filtering of the question to see if it is of interest at the present time, like the following:    e.g. arduino is in my list of favorites, but the other two in each question are not.


"Happiness is.. Having friends with the same mental disorders as yours."  I was just wondering if this sentace is grammatical or should it be "you" at the end?  Either way; it's very funny!  Thanks

Is it correct to say      Dilbert bought the same car as me.   If it is, what are other sentences for other pronouns such as he?     Dilbert bought the same car as David/he/him   I know you can say      Dilbert bought the same car as yours   when you refer to or compare objects.


The problem is trivial if at least one of $x$ or $y$ is greater than $1$.  So all we need is to proof that $x^y+y^x > 1 \ \forall x,y \in (0,1)$.

This is a classic problem, but I haven't seen it on the site before.     Suppose $x$ and $y$ are real numbers that both lie in the interval   $(0,1)$. Prove  $$x^y+y^x>1.$$   The following spoiler box contains a hint that indicates the solution I know. Does anyone know a more natural solution?       Use Bernoulli's inequality to show $$x^y\ge \frac{x}{x+y}.$$   Edit: I recently learned the source is the 1996 French math olympiad.


I am regularly getting an error message from a program that purports to be an OS X Install program.  I have no idea how this is starting, or where it is from, but it appears after reboots too, and I don't like it.  I'm running the El Capitan 10.11 Beta (15A278b), so there is a possibility it's connected to that.  After trying to update some other apps from the MAS, I get an error message which indicates it's a Yosemite Beta Installer.  Anyone know where this can come from, and how I can stop it?

This is just silly:    If I try accepting (no, I wouldn't go through with it), it just says that the update is unavailable.  So why does it ask me to downgrade, and how do I get rid of this?


how can I get the length / size of a map in "ng-show"?  var map = {    "key1": "value1,    "key2": "value2,    "key3": "value2 }   UPDATE 01  <button ng-show="Object.keys(map).length>0"></button>   or   <button ng-show="_.size(angular.copy(map)>0"></button>   UPDATE 02    where and how to set the $scope.Object = Object; ??  when I set that I got the following error:     Error: [$parse:isecobj] Referencing Object in Angular expressions is   disallowed! Expression: Object.keys(selectedIdeas).length>0

What's the fastest way to count the number of keys/properties of an object?  It it possible to do this without iterating over the object?  i.e. without doing  var count = 0; for (k in myobj) if (myobj.hasOwnProperty(k)) count++;   (Firefox did provide a magic __count__ property, but this was removed somewhere around version 4.)


Let $G,H$ be a group.  Consider the following statement:  If $G$ and $H$ each have more than one element then,   $(i)$ $Z(G\ast H)=\{e\}$  $(ii)$ $G\ast H$ is an infinite group.  How can I get $(i)$ and $(ii)$?.I am seeking a suggestion. Thanks

Let $A$ and $B$ be two groups and let $G=A*B$ be their free product. Suppose both $A$ and $B$ are nontrivial. I want now to prove that $G$ is infinite and that $Z(G)$ is trivial.  I think I can prove that $G$ is infinite using this argument: two reduced words of $A*B$ are equal if and only if they have the same length and the ith letter of the first word is the same as the ith letter of the second one. Hence one can find a reduced word of $G$ of length arbitrarily big (since we are sure it won't be equal to a shorter word). Do you think it works? Has anyone another suggestion?  On the other hand, I don't really have a clue for the second part except trying to analyze a long list of cases of reduced words and prove for each one that the only element with which they commute is the identity. Does anyone have a smarter idea?  Thanks in advance!


I have a simple program that reads all the files from a given directory into an array. The array is then looped through and the file names listed in a JFrame as individual JLabels.   I am also able to read the file extension using this code:                   String extension = "";                 int i = FileName.lastIndexOf('.');                 if (i > 0) {                     extension = FileName.substring(i+1);                 }   This works fine, however when I try to use the extension in an if statement like this:                      if(extension == "java")                      {                         System.out.println(FileName);                      }                      else                     {                       System.out.println("error");                     }   all i get is error statements in the console, even though there are several java files in the directory (as can be seen in the results JFrame!)  Can anyone tell me what the problem is? Thanks!

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?


I guess the title sums up my question perfectly.  Some examples:   "Disk Utility was installed on the Recovery partition" or "Disk Utility was installed in the Recovery partition". "Download and save your file on the Files partition" or "Download and save your file in the Files partition".    Is only one usage correct? Or are both on and in acceptable?  And, would the answer be different if the meaning of partition was different? For example, partitions referring to countries (e.g. divided into states) as opposed to a hard drive as per my examples above.

When I say "programs to install on a new PC" it sounds alright to me, but I'm not sure if it's the correct usage. Which one of the following should I use?   Programs to install on a new PC Programs to install in a new PC Programs to install to a new PC


In hypothesis testing, alternative hypothesis doesn't have to be the opposite of null hypothesis. For example, for $H_0: \mu=0$, $H_a$ is allowed to be $\mu>1$, or $\mu=1$. My question: Why is this allowed? What if in reality, $\mu=-1$ or $\mu=2$, in which case if one applies, say, likelihood ratio test, one may (wrongly) conclude that $H_0$ is accepted, or $H_0$ is rejected and hence $H_a$ is accepted?   What about this proposal: $H_a$ should always be the opposite of $H_0$? That is, $H_a: H_0$ is not true. This way, we are effectively testing only a single hypothesis $H_0$, rejecting it if the p-value is below a predefined significance level, and not have to test two hypotheses at the same time that can be both wrong.

I saw a lot of times claims that they have to be exhaustive (the examples in such books were always set in such way, that they were indeed), on the other hand I also saw a lot of times books stating they should be exclusive (for example $\mathrm{H}_{0}$ as $\mu_1=\mu_2$ and $\mathrm{H}_{1}$ as $\mu_1>\mu_2$) without clarifying the exhaustive issue. Only before typing in this question I found somewhat stronger statement on the  -- "The alternative need not be the logical negation of the null hypothesis".  Could someone more experienced explain which is true, and I would be grateful for shedding some light on the (historical?) reasons for such difference (the books were written by statisticians after all, i.e. scientists, not philosophers).


I'm using 18.04 Linux operating system on my device. How to install Feem software on my system?

I just read . It talks about downloading an AppImage.     Yes, Linux; the Linux packages is distributed as an .appimage for 32-bit and 64-bit distributions, and should run across all major Linux distributions without any issues. The team currently have no plan to provide a native .deb (or .rpm) installer.   What are AppImages? How do they differ from snaps?


Prove that gcd of a list of numbers say gcd(a, b, c, d) = gcd(a, gcd( b, c, d)). I know that the above-stated method of finding gcd of a list of numbers works. but I am not able to prove it. Can someone help with this?

Prove $\gcd(a,b,c)=\gcd(\gcd(a,b),c)$ for $0\ne a,b,c\in \Bbb{Z}$. I tried solving it with sets but I sense there are some details I am missing. I would truly appreciate your reference.


I need some clarity on the usage of who and whom, and which is the correct sentence between these two?   The man WHOM I thought was thoroughly honest proved to be a swindler. The man WHO I thought was thoroughly honest proved to be a swindler.

Many times, I've been asked the difference between "who" and "whom". I myself know the difference, but it is hard to explain to others. What is the easiest way to explain it to those with a basic understanding of English? A mnemonic (if possible) would help.


I am presently viewing the desktop of a remote machine running Rasbian (raspberry pi) on my local machine running Linux Mint using RealVNC. Teamviewer also works. But I don't want to see that remote machine's entire desktop, I just want to view/forward two or three of the remote machine's open windows on my local machine's desktop, as if they were windows created by local gui processes.   IOW, remote machine has a desktop, and on that desktop are several windows running processes. My local machine also has a desktop and there are a few open windows on it, too. I want to be able to add some of the remote machine's windows to my local desktop, not the entire remote desktop. And be able to re-arrange them on my desktop just as if they were windows running on my local machine, and (he asks too much!) be able to interact with the remoted windows just like I can with the local windows. Does this makes sense?

I want to remote login to another laptop to continue working on session left over. VNC is slow because it's bandwith hog. I know (or I think I know) that it's not latency, it's bandwith because the first update from the top of screen or the top of recently changed view occurs very fast, but the entire redraw takes time. I believe that X doesn't send the pixelmap, but instructions on how to redraw screen. So I'd like to use X.  Question: Is there a way for me to say, to all the applications, please now migrate to the X server available remotely? Or can I make my computer think that what it calls :0.0 is no longer attached to the monitor, but is now on a remote machine. (And can I reverse this process so that I can switch back to the other laptop whenever I want)?


Using \overbrace with Minion Math yields the brace being printed over the equation. Latin Modern and TeX Gyre Pagella works fine, so it seems a font specific problem.  This happens in inline and display math; both with XeLaTeX and LuaLaTeX. \underbrace seems to work fine. Could be that the MATH table is incorrect? Can it be fixed somehow with XeLaTex? (For some other reason I can't use LuaLaTeX) \documentclass{article}  \usepackage{amsmath} \usepackage{unicode-math} \setmathfont{Minion Math}  \pagestyle{empty} \begin{document}  \(\vec{e}_{i}=(\overbrace{0,\ldots,0,\underset{i}{1},0,\ldots,0}^{n})\), $i=1,2,\dots,n$  \end{document}

I'm trying to experiment with Minion Math for the first time. Unfortunetly   \setmathfont{Minion Math}   under XeLaTeX causes the following error which I don't understand:  ! Font \l_fontspec_font has only 8 fontdimen parameters. <recently read> \l__um_font   l.147     \setmathfont{Minion Math}  ? h To increase the number of font parameters, you must use \fontdimen immediately after the \font is loaded.   LuaLaTeX runs fine. Complete set of font commans is as follows:  \usepackage{fontspec} \defaultfontfeatures{Ligatures={TeX}} \setmainfont{Minion Pro} \setsansfont[Scale=MatchLowercase]{Corbel} \setmonofont[Scale=MatchLowercase]{Myriad Pro} \usepackage[math-style=ISO,bold-style=ISO]{unicode-math} \setmathfont{Minion Math}   Log files gives the following information just before the error:  \g__fontspec_family_MinionMath_int=\count276 ................................................. . fontspec info: "defining-font" .  . Font family 'MinionMath(0)' created for font 'Minion Math' with options . [Ligatures={TeX},BoldItalicFont={},ItalicFont={},Script=Math,SizeFeatures={{S ize=10.95-},{Size=8-10.95,Font=Minion . Math,Style=MathScript},{Size=-8,Font=Minion Math,Style=MathScriptScript}}]. .   .  This font family consists of the following NFSS series/shapes: .   . - 'normal' (m/n) with NFSS spec.: <10.95->"Minion . Math/OT:script=math;language=DFLT;mapping=tex-text;"<8-10.95>"Minion . Math/OT:script=math;language=DFLT;+ssty=0;mapping=tex-text;"<-8>"Minion . Math/OT:script=math;language=DFLT;+ssty=1;mapping=tex-text;" . - 'small caps'  (m/sc) with NFSS spec.:  . - 'bold' (bx/n) with NFSS spec.: <->"Minion . Math/B/OT:script=math;language=DFLT;mapping=tex-text;" . - 'bold small caps'  (bx/sc) with NFSS spec.:  .................................................   What should I change in my source file?


I'm installing a small baseboard heater in a back bedroom, adding it to a 240V circuit with two heaters already installed in other rooms. I mainly use the two heaters on low when I am away to prevent pipes from freezing. I heat with wood when there. I would like to be able to totally cut off power to the newly added third heater. This bedroom gets closed off when I am away and since the heater has a built in thermostat with lowest setting of 32degrees it will likely come on when the room is closed off. I don't need or want that...waste of electricity! No pipes back there. I would like to install a switch to the line before it reaches the heater to simply cut the power to that back bedroom heater when I'm away.   Would there be any issues with this type set up?  Do I need any special kind of switch or will a basic 20amp 120/240V light switch do the trick?  Thanks.

I posted this question but for some reason I can't get back into my account:    Most things I see with 220V have both hot legs going through the switch or relay, current "returns" through the switch.  Is it against code to wire one leg directly to the equipment and the other leg is switched as opposed to having both legs switched.  It seems useless and a waste of wire to switch both legs.  Basically  vs  (minus the GFCI as I'm not allowed to have that)  As a bonus question.  I assume I need a "motor rated switch" as standard switches can weld due to the high startup current.  Is  one legal\safe?


This is what I have attempted, and may give a better gist of the question I'm trying to ask: var x = "run"; var y = "Function"; var xy = x + y;  function runFunction() {     console.log("Function has been called."); }  xy();   What am I doing wrong here?

I have the name of a function in JavaScript as a string. How do I convert that into a function pointer so I can call it later?  Depending on the circumstances, I may need to pass various arguments into the method too.  Some of the functions may take the form of namespace.namespace.function(args[...]).


I'm writing a simple program and in it I need to get a user's input for yes/no (I'm using Scanner, UI, for this) like so:      System.out.println("Do you know the insulation capacity? (y/n) ");     String IC = UI.nextLine();   And that works perfectly fine, but I have trouble in the next section, where I check the string in an if statement:      if(IC == "y" || IC == "Y" || IC == "yes" || IC == "Yes"){ //four options of saying "yes"         System.out.print("What is the insulation capacity? ");         m = UI.nextDouble();     }else if(IC == "n" || IC == "N" || IC == "no" || IC == "No"){ //four options of saying "no"         findM();     }else{         System.out.println("Answer was not clear. Use y, n, yes, or no.");         checkM();     }   When I run the program, the else is always executed, even if IC is Y, y, Yes... etc.  Why is this the case and how do I get this to work?  Thanks,  -Justice

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?


$E=mc^2$ states that Energy equals matter times the speed of light. So, can't we just turn all the energy into mass and it would come out to a fixed amount of matter?

In popular science books and articles, I keep running into the claim that the total energy of the Universe is zero, "because the positive energy of matter is cancelled out by the negative energy of the gravitational field".  But I can't find anything concrete to substantiate this claim. As a first check, I did a calculation to compute the gravitational potential energy of a sphere of uniform density of radius $R$ using Newton's Laws and threw in $E=mc^2$ for energy of the sphere, and it was by no means obvious that the answer is zero!  So, my questions:   What is the basis for the claim – does one require General Relativity, or can one get it from Newtonian gravity? What conditions do you require in the model, in order for this to work? Could someone please refer me to a good paper about this?


Here's my code:  def date_it(month, day, year):     month= ('January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'November', 'December')     d=int(day)     y=int(year)     print month[5],d,",",y   OUTPUT: June 17 , 2016 How do I get rid of the space between 17 and , ?

In python, if I say  print 'h'   I get the letter h and a newline.  If I say   print 'h',   I get the letter h and no newline.  If I say  print 'h', print 'm',   I get the letter h, a space, and the letter m.  How can I prevent Python from printing the space?  The print statements are different iterations of the same loop so I can't just use the + operator.


My situation and goal: I have a Asus Laptop which I upgraded from Win7 to Win10 a year ago. So far so good. My Account is since ever defined as administrator, but actually it can't proceed administrator tasks.  I want to delete driver files. The path is in the title of the question. My account is an administrator account but I can't delete files in this folder.   When I move files from folder A to folder B it happens that I have to confirm moving them or I have to give allowance to applications to install files. This experiences brought me to the point that I see something with the administrator rights is not correct. I assumed that my account has problems with the administrator rights and I have to fix these before I can delete the targeted files.  What I tried to solve the administrator issue:  I tried several ways to get administrator rights.  1) I tried to change account typ from standard to administrator. Not possible, because when I choose this option the button to accept the choice gets inactive. button gets inactive when I select administrator. And as you can see the account is defined as administrator, but is from type standard.    2) I activated an administrator account via cmd-window and "net user administrator /active:yes". It worked but this account is not able delete files which need administrator rights. It seems this account is an administrator account but has not the rights for it.  3) I tried to change the administrator rights for my standard account and administrator account in "Save mode" of windows. the same situation like in point 1.  4) By solving the administrator issue, I found out that my windows lakes functionalities. I wanted to take control over this problem by using the "Computer Manager", but the area where you can manage accounts and group is not existing. The local group policy window doesn't work. (see below in the comments the screenshots)  Something in the system is messed up. What is wrong or what else can I do to make it possible to control this kind of files in Windows 10?

I accidentally disabled my admin account.  After I login to another account I found I can not get admin rights, because all admin accounts on my computer are disabled.  I clicked on 'run as administrator' but only see a smart card choice (all the admin accounts are disabled so no choice provided)    I don't want to re-install my OS, help!    Details:  I have account A on my computer.    I got a new computer so I want to give the old one to my mother.    Creating a new user account B for her and disable account A.    Logout and restart.    Successfully login B, now I found I could not get admin rights because no account choice is provided.    More informations about my machine:  OS is Windows 10 and my admin account is a Microsoft Account.  I have an arch-linux installed on my computer and dual-boot it using GRUB, so maybe I can not use safe mode.


I've been reading a bit about the confidence intervals on Wikipedia. The section on  says:  A 95% confidence level does not mean that for a given realized interval there is a 95% probability that the population parameter lies within the interval (i.e., a 95% probability that the interval covers the population parameter). According to the strict frequentist interpretation, once an interval is calculated, this interval either covers the parameter value or it does not; it is no longer a matter of probability. The 95% probability relates to the reliability of the estimation procedure, not to a specific calculated interval.  I read through an  making the same point. It concludes by saying:  The nature of confidence intervals is that they can encompass the true value with some chance. In our example, a confident interval tends to encompass the true value in 90% of trials. But that does not mean that for some specific interval, there is a 90% chance of finding the true value within the interval.  But I really don't understand the point of this argument. What is the difference between saying "there is a 90% probability that the true value is within our interval" and "there is a 90% probability that our interval included the true value"? Is it just a philosophical issue or can it really lead to incorrect conclusions?

It seems that through various related questions here, there is consensus that the "95%" part of what we call a "95% confidence interval" refers to the fact that if we were to exactly replicate our sampling and CI-computation procedures  many times, 95% of thusly computed CIs would contain the population mean. It also seems to be the consensus that this definition does not permit one to conclude from a single 95%CI that there is a 95% chance that the mean falls somewhere within the CI. However, I don't understand how the former doesn't imply the latter insofar as, having imagined many CIs 95% of which contain the population mean, shouldn't our uncertainty (with regards to whether our actually-computed CI contains the population mean or not) force us to use the base-rate of the imagined cases (95%) as our estimate of the probability that our actual case contains the CI?   I've seen posts argue along the lines of "the actually-computed CI either contains the population mean or it doesn't, so its probability is either 1 or 0", but this seems to imply a strange definition of probability that is dependent on unknown states (i.e. a friend flips fair coin, hides the result, and I am disallowed from saying there is a 50% chance that it's heads).  Surely I'm wrong, but I don't see where my logic has gone awry...


I've started testing different DEs for Ubuntu because of the Unity news last week. Some of them use Wayland and I like them, but since sometimes I use xrandr to emulate a higher-than-native resolution with newrez I'm left wondering what the tools would be to achieve this on Wayland.  Any suggestions on how to achieve this?

Old title - "change resolution to 1280x1024 using xrandr gives: X Error of failed request: BadValue (integer parameter out of range for operation)"  I have installed a fresh Ubuntu 17.10 and have a monitor with 5:4 resolution. settings has no resolution higher than 1024x768. But I need the resolution 1280x1024 (5:4).  I use the default motherboard graphics card:  # lspci|grep VGA 00:02.0 VGA compatible controller: Intel Corporation 4 Series Chipset Integrated Graphics Controller (rev 03)   Also xrandr gives the following:  $ xrandr Screen 0: minimum 320 x 200, current 1024 x 768, maximum 8192 x 8192 XWAYLAND0 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm    1024x768      59.92*+   I tried to add the 1280x1024 resolution using xrandr. so first created the resolution information using gtf:  $ gtf 1280 1024 60    # 1280x1024 @ 60.00 Hz (GTF) hsync: 63.60 kHz; pclk: 108.88 MHz   Modeline "1280x1024_60.00"  108.88  1280 1360 1496 1712  1024 1025 1028 1060  -HSync +Vsync   Then added to resolutions:  xrandr --newmode "1280x1024_60.00"  108.88  1280 1360 1496 1712  1024 1025 1028 1060  -HSync +Vsync   then again did the command: xrandr --addmode XWAYLAND0 1280x1024_60.00  Then nothing changed. When I tried to change it using xrandr --output XWAYLAND0 --mode 1280x1024_60.00 --rate 60 But an error occurred:  $ xrandr --output XWAYLAND0 --mode 1280x1024  --rate 60 X Error of failed request:  BadValue (integer parameter out of range for operation)   Major opcode of failed request:  140 (RANDR)   Minor opcode of failed request:  7 (RRSetScreenSize)   Value in failed request:  0x0   Serial number of failed request:  21   Current serial number in output stream:  22   I don't know what did I do wrong. Or how to change resolution to the correct one: 1280x1024


I have a split window setup for terminator and was wondering if there was a way to set it up such that the default is to run the commands from one window in the other.  I know that what I need to do is find a way to append "> /dev/pts/17" (my terminator window) to the end of every command. Is the way to do this by editing .bashrc?

I want to run a command foo on one terminal and pass the result to another terminal. Is it possible to do this ?


class WordCount {     String resource;     void read () throws IOException     {          File file = new File("C:\\Users\\Desktop\\read.txt");            BufferedReader br = new BufferedReader(new FileReader(file));           while ((resource = br.readLine()) != null)          {                  resource.trim();          }          System.out.println(resource.length());          br.close();     } }

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?


Consider there are two divs like showing bellow.

   I want the sub div to be vertically centered not to the whole page but to the main div.

I want to center a div vertically with CSS. I don't want tables or JavaScript, but only pure CSS. I found some solutions, but all of them are missing Internet Explorer 6 support.
Div to be aligned vertically
   How can I center a div vertically in all major browsers, including Internet Explorer 6?


I am keep getting output as below:  Inside AuthenticationFilter.. Inside Session!   why session not getting cleared after browser closed? I even kepted page session=false inside index.jsp too , but still not working.. Please someone look into below code and help me getting session cleared after browser window closed.  Below is the code:  index.jsp  <%@ page session="false" %> <%  /* ServletContext context= getServletContext(); RequestDispatcher rd= context.getRequestDispatcher("/login"); rd.forward(request, response); */  response.sendRedirect("login");  %>   loginServlet  import java.io.IOException; import java.io.PrintWriter;  import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession;  /**  * Login servlet.  */  @WebServlet("/login") public final class LoginServlet extends HttpServlet {      private HttpSession session = null;     private RequestDispatcher rd = null;      /**      * Respond to a GET request for the content produced by      * this servlet.      *      * @param request The servlet request we are processing      * @param response The servlet response we are producing      *      * @exception IOException if an input/output error occurs      * @exception ServletException if a servlet error occurs      */     @Override     public void doGet(HttpServletRequest request,                       HttpServletResponse response)       throws IOException, ServletException {          System.out.println("Inside Login Servlet...");          PrintWriter out = response.getWriter();         out.print("<h3> This is login servlet poage ... </h3>");      } }    AuthenticationServlet  import java.io.IOException;  import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.annotation.WebFilter; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession;   @WebFilter("/*") public class AuthenticationFilter implements Filter{      private HttpSession session = null;      public void init(FilterConfig arg0) throws ServletException {}        public void doFilter(ServletRequest req, ServletResponse resp,           FilterChain chain) throws IOException, ServletException {          System.out.println("Inside AuthenticationFilter..");          HttpServletRequest request = (HttpServletRequest) req;         HttpServletResponse response = (HttpServletResponse)resp;          session = request.getSession(false);         if(session != null && !session.isNew()) {             System.out.println("Inside Session!");         } else {             getAccessToken(request, response, chain);             chain.doFilter(request, response);         }      }        public void destroy() {}        private void getAccessToken(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException {          session = request.getSession();         System.out.println("Created new  Session!");     }  }

I have the following implementation of HttpSessionlistener  public class SessionListener implements HttpSessionAttributeListener, HttpSessionListener {   public void attributeAdded(HttpSessionBindingEvent event) {    ...  }   public void attributeRemoved(HttpSessionBindingEvent event) {      ... }  public void attributeReplaced(HttpSessionBindingEvent event) {  }  //HttpSesion creation & destruction public void sessionCreated(HttpSessionEvent event) {     HttpSession session = event.getSession();     //log created time   }  public void sessionDestroyed(HttpSessionEvent event) {     HttpSession session = event.getSession();     long destroyedTime = System.currentTimeMillis();     //log destroyed time  }   }  Basically i log the session creation and destruction time. But if the session is long (default to 30 minutes), and user closes browser meanwhile, the   sessionDestroyed    is not called ?  Why is that ?  Is there a workaround to log exactly the when the session was destroyed (when user closes the browser)? Should'nt be this be the browser's problem, to kill the session when it is closed ?  Is there any interface that i have to implement for this to work ?  Thank you !


I was on the Ubuntu Software Center and downloaded "C, C++ and Objective-C compiler(clang)." I didn't see it anywhere so i went to "search your computer and online resources" and didn't see it anywhere. I went to Ubuntu Software Center and went to the "installed" tab and searched for it. But it was not there (by the way it said that it was installed when I searched for it again except this as in the all software center in Ubuntu software center). This was weird and annoying so I went to terminal and entered open  C, C++ and Objective-C compiler but it said that it couldn't get a file descriptor referring to the console. All helpful answers will be fully appreciated.   BTW my question is not a duplicate of "How can I know what programs some apt-get package contains?" as suggested by muru as one question is asking about how can they know what a package contains where my question is asking about where my download even is, obvious difference

I would like to know what some specific package installs, for example, when installing ncurses, I have found that TAB key expands:  sudo apt-get install ncurses-   to show:  ncurses-base      ncurses-doc       ncurses-hexedit ncurses-bin       ncurses-examples  ncurses-term   How could I know what, say, ncurses-term installs? I am interested mainly in programs, but libraries and any other filetypes could be useful too.  Command-line method, if possible, would be preferred (any others accepted too).


Given  for calculating the distance to an object as long as you have a picture of the object and know the actual height of the object...  distance to object (mm) = focal length (mm) * real height of the object (mm) * image height (pixels)                           ---------------------------------------------------------------------------                           object height (pixels) * sensor height (mm)   What would be an accurate range of ratios of Focal Length and Sensor Height to approximate a human eye?  I think this question is sufficiently different from  and

For example, if I have a lens that is 16mm-50mm, which focal length would be the closest to the human eye's view? (I don't have a camera yet, so I'm just curious.)   Would 50mm be more zoomed in than "normal"?  I imagine 16mm would be wider than the normal human point of view?


I want to use fancyhdr in the letter document class to define a custom header for the first page only. I know that I can use \fancypagestyle to do this (as is discussed ), but the problem is that my first-page header contains several rows, and I don't want the following pages to contain white space at the top that results from the 'missing' header. Is there a fix for this?

I have a document class that auto generates header from some user input. The problem is the first page should have a different page header than the others and the headline can be multi line. So \headheight is too small. Here is a demonstration of the problem:  \documentclass[twoside]{scrartcl} \newcommand{\longfirstpagehead}{% \begin{minipage}{10cm} some\\long\\text\\text\\text\\text\\text\\text \end{minipage}} \newcommand{\normalhead}{normal} \usepackage{scrpage2}  \newpagestyle{firstpage}{%     {\longfirstpagehead\hfill} %twoside links     {\longfirstpagehead\hfill} %twoside rechts     {\longfirstpagehead\hfill} %oneside     (\textwidth,1pt) }{%     {\pagemark\hfill} %twoside links     {\hfill\pagemark} %twoside rechts     {\hfill\pagemark} %oneside } %  \newpagestyle{normal}{%     {\normalhead\hfill} %twoside links     {\normalhead\hfill} %twoside rechts     {\normalhead\hfill} %oneside     (\textwidth,1pt) }{%     {\pagemark\hfill} %twoside links     {\hfill\pagemark} %twoside rechts     {\hfill\pagemark} %oneside } %    \pagestyle{normal} \AtBeginDocument{     \thispagestyle{firstpage}}  \usepackage{blindtext} \begin{document}     %\vspace*{1cm}     \blindtext      \blindtext     \pagebreak \end{document}   I tried to read the height with \settototalheight and:   add a \vspace at beginning of document (unnice hack):  still the bad box warning (of cause) first section has different alignment  manually change \headheight in pagestyle  text height and page foot is wrong (can't change this because some scoping?)  use Komascript in pagestyle  \recalctypearea warning  geometry in pagestyle  pretty much the same problem like the manual attemp    So I would like to change the \headheight for the pagestyle firstpage, but the page should still have the same page margins, etc. The problem is that this has to work with \thispagestyle. (Better Ideas are also welcome) Something like \thispagegeometry in geometry would be great. ;)


I'm looking for a way to make the D figure in LaTeX. Please help :)

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


Downloaded images failed checksum validation   I tried to install Ubuntu on a Nexus 7. I have tried several times in the last month. I followed all directions to the letter, and went through all the troubleshooting steps. I Re-downloaded the Ubuntu Core Nexus 7 installer, but I still always get the above notice.  Any suggestions?

I am trying to install Ubuntu on my Nexus 7 as mentioned in the  . However, when I run the Ubuntu Nexus7 installer I get an error saying that it cannot download the content (My connection is working correctly). I tried to do it manually as mentioned the official wiki post as well, they said I should download the image from   but it shows the 404 error! Help me please, I have already unlocked the bootloader and lost all my data.


Let $a, b$ integers such that $ab+2a+3b=93$. Find all solutions integers.  What I tried is $ab+2a+3b=b(a+3)+2a$ but i don't see how to proceed to related $a$ and $b$ such that see it multiplying and play with combinations of  $93=3*13$.

Find one integer solution to the following Diophantine equation:   \begin{equation*} \\\forall \,x,y \in \mathbb{Z}\\ 6xy + x - y = 274 \end{equation*}   The resultat ist $x = 9$, $y = 5$ (Obtained with  )  I need to know a method that allows me to reach such a result. How can I calculate the value of these two variables in a Diophantine equation? For example: 6xy + x - y = 458


In this monostable circuit the C1 capacitor is reverse biased. When T1 is closed and C1 is discharged what will happen on the right side of C1?   Will it charge up to 0.6 volts so that T2 can be opened and then discharge again over the base-emitter line and than charge through R2?   That would mean that the polarized capacitor could be loaded reverse biased. Is that true?

I know that I mustn't connect an electrolytic capacitor reversely. It will explode if I apply the reverse voltage long enough.  But, what happens if the reverse voltage is applied for a short time? For example, a fault occurs in the circuit and the capacitor becomes reverse biased or exposed to AC voltage for a short time, but it still looks OK from outside. Does the internal physical and chemical structure of the capacitor change permanently? Would it still have the rated capacitance, voltage and life time? Is it okay to keep it using if it doesn't explode? I feel that the answer is "no", but I'm looking for an explanation for it.