after the change of the video card (both nvidia gtx), every time after the boot the display has a bigger scale. I need after every boot to change the display scale to 200% and after reset to 100%. My configuration has 2 display, one connected via VGA to the motherboard, and the other via HDMI to the nvidia card.

So I was configuring VS code on my Notebook when suddenly I noticed that my interface font got really small on my desktop, terminal and files. I use Gnome Tweaks Tool to increase my scaling factor to 1,15 , but, even though it was active, the font stayed tiny. The solution I found was moving my scaling factor, which instantly fixed my font issue, however, every time I restart my Notebook the font gets tiny again and I have to repeat the process. I tried reseting my font configuration using this command, but had no success. gsettings reset org.gnome.desktop.interface text-scaling-factor  I also tried using the command dconf reset -f /  Finally, I tried using dconf-editor, but still had no success altering the font rendering DPI or changing the scaling factor. All of the steps I mentioned fixed my fonts temporarily, but the issue still persists when I restart my Notebook I am out of ideas and even considered getting a fresh Ubuntu install by now... My video card: NVIDIA GeForce GTX 1050 GPU


Is this product:  \begin{align*} \prod_{\text{$p$ prime}}\frac{p^2+1}{p^2-1} \end{align*} rational? What is the value of it? What about for the natural numbers $p>1$?

I have shown that the infinite product $$\prod_{p \in \mathcal{P}}\frac{p^2+1}{p^2-1}$$ is equal to $\frac{5}{2}$ (pretty remarkable!). I have checked this numerically with Wolfram Alpha for up to $500000$ primes and it seems true.  I was wondering if this result is recorded anywhere?  Also if true, does this mean that there aren't infinitely many primes of form $p^2+1$?


Suppose that $A$ is an $n \times n$ matrix and that for all $B$ of size $n \times n$, $AB=BA$. My question is why is $A$ of the form $A=CI$ where $C$ is a scalar and $I$ is the identity matrix?

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!


Since when going after the road-map, firefox 57 will be released on 14.11.207.   Now my problem is that I use a whole lot of legacy add-ons I want to keep working with.   So how can I prevent firefox from updating via the repositories?

Because of  I'd like to prevent apt-get upgrade and Update Manager from updating the "libgtk2.0-0" package.   How can this be achieved?


Hi I have Vado 3 Specialized ebike with 700x47c tyres fitted. Need to change soon. What are your thoughts on downsizing to a 700x38c tyre to reduce road friction and improve rolling on tarmac?

We often get questions on bicycles.stackexchange about fitting wider or narrower tires to bicycles. We have a large number of these with answers suiting the specific bike or style of bicycle in question, but I have been unable to find one that provides a generic answer covering off all things that need to be considered. For most bicycles, the answer is the same regardless of the specific style and sizes of tires in question.   This is intended as a canonical question that we can point closed questions to.


I wanted to reduce my demense count by giving up some of my titles to my Councillors, for example my Spymaster who is Mayor. I granted them one of my duchies and now he's kicked off the Council, leading to a decrease in his opinion towards me, plus a landed title:  How does this mechanic work?

I've noticed several times that if I have a landless council member and I grant him a landed title, his seat becomes vacant and I cannot appoint him again.  After an unspecified amount of time he becomes eligible again.  Why is that? Is that a bug or is there a reason for that?


I find two main definitions for the norm of a matrix or linear operator.  First definition: $\lVert A\rVert := sup \{|A(\frac{x}{|x|})|: x\neq 0 \} $  Second definition: $\lVert A\rVert := sup \{|A(\frac{x}{|x|})|: |x| \leq 1 , x\neq 0  \} $  Why are those two equivalent? I am sure it has something to do with linearity, but I can't see the answer.  I know, since the unit ball is compact, the superemum is attained for some x on or inside the unit ball. Why must the maximum lie on the surface unit ball?  Help would be appreciated.  Thank you

How do you prove that these four definitions of the operator norm are equivalent? $$\begin{align*} \lVert A\rVert_{\mathrm{op}} &= \inf\{ c\;\colon\; \lVert Av\rVert\leq c\lVert v\rVert \text{ for all }v\in V\}\\ &=\sup\{ \lVert Av\rVert\;\colon\; v\in V\text{ with }\lVert v\rVert\leq 1\}\\ &=\sup\{\lVert Av\rVert\;\colon\; v\in V\text{ with }\lVert v\rVert = 1 \}\\ &=\sup\left\{ \frac{\lVert Av\rVert}{\lVert v\rVert}\;\colon\; v\in V\text{ with }v\neq 0\right\}. \end{align*}$$


Suppose $U_1,...,U_n$ are independent Bernoulli random variables taking values $0$ or $1$ with $Pr(U_i=1) = \theta$ and $Pr(U_i=0)=1-\theta$ Let $S = U_1+...+U_n$ be the number of $U_i$ equal to one.  Show $S \sim Binomial(n, \theta)$  I'm unclear as to what I need to show in order to achieve this. Would it be enough to show: $(1)$ That the sample of space of $S$ is the same as a Binomial variable with such parameters. $(2)$ The probability of each element of the sample space and hence the probability distribution of $S$ is also the same as a Binomial variable with such parameters. Or is there something specific way to show that $S$ is a Binomial random variable?

Let $\{X_n, n \geq 1\}$ be iid Bernoulli random variables with $\Pr(X_1 = 1) = p = 1 - \Pr(X_1 = 0)$ and let $S_n = \sum\limits_{i=1}^n X_i$ be the number of successes in $n$ trials. Show $S_n$ has a binomial distribution by the following methods:  1.) Prove for $n\geq0,$ $1\leq{k}\leq{n+1}$  $$\Pr(S_{n+1} = k) = p\Pr(S_n = k - 1) + q\Pr(S_n = k)\text{ where }q = 1-p.$$  2.) Solve the recursion using generating functions.  For the first method, I think I need to use convolution of $n + 1$ Bernoulli rvs, but I cannot immediately see the progression. For the second method, I don't exactly understand how to proceed either. This is problem 1.2 from Resnick's Adventures in Stochastic Processes.


I'm trying to format a table in latex to look like the image I've attached; however, I don't know how to create a new row that isn't affected by the formatting of the previous ones. Thank you for your help, and apologies for the mediocore illustration.

Here is a simple table.  I want to merge 4 cells. I want to combine the three "this" cells area in this table. I thought I have to use multirow and multicolum at same time. However, I could not find how to use it.  If possible, could you post the modified LaTeX source code?     My LaTeX code:  \documentclass{article} \usepackage{multirow}% http://ctan.org/pkg/multirow \usepackage{hhline}% http://ctan.org/pkg/hhline \begin{document}  \begin{table}[ph] \begin{center} \begin{tabular}{c|c|c|c|c} \hline \multirow{2}{*}{Raaa (k)} & \multicolumn{4}{c}{C ()} \\ \hhline{~----}  & 3.3 & 2.5 & 1 & 0.5 \\ \hline \multirow{2}{*}{Raaa (k)} & \multirow{2}{*}{this} & this & 0.5 & 0.6\\ \hhline{~~~--}            &                       & this & 0.7 & 1.2 \\ \hline \end{tabular} \caption{R, C ripple size} \label{T:peak} \end{center} \end{table} \end{document}


Is there a way to calculate this limit?  $$\lim_{x \to +\infty} x \left( \sqrt{(1+\frac{a}{x}) (1+\frac{h}{x})} -1 \right)$$  I know it's equal to $\frac{a+h}{2}$, but what method can I use to calculate this? I can't use l'Hopital.

Hi I have a question regarding finding the values of limit for the following question.  Let $a, b \in \mathbb R$. Find the limit $$\lim_{x\to+\infty}\left(\sqrt{(x+a)(x+b)}-x\right)$$


I know this might be far fetched. In normal everyday life, we have huge amounts of data traveling through the air in the form of electromagnetic radiation. But what if instead of transmitter data through this channel we instead transmit low energy power. Where by at the receiver side we use the antenna or a custom built transducer that will be able to convert this transmitted power into a clean 5V DC voltage. Is this even feasible?

Why can energy invested in RF radiation not be harvested fully? What are the main factors that affect this? Is there any significant research nowadays that fully describes this process? I stand on the conclusion: "Energy moves from one form to another.", but in this case why can it not be harvested in that quantity to use it for powering low-power devices or store it in significant quantities in some batteries for later use? Why is it not profitable nowadays and why is it not used today like energy from water, wind and other energy sources?


I have a number in system tray which is 7 in this picture:    What is it? If it is a number of some messages, then how to see them?  If I hover mouse it says    but I found no way to see these notifications.

The notification tray icon shows the wrong count:    As a temporary workaround to the annoyance of this I thought I would disable the count. This menu option has no effect at all:    Is this a known defect in the current build of Windows 10 (Version 1803, Build 17134.284)? I can't find anything on Microsoft Connect.


Let $f: \mathbb{R}^{2} \rightarrow \mathbb{R}$ of class $C^{\infty}$ with $f(x,0)=f(0,y)=0$ for all $x, y \in \mathbb{R}$. prove that there exists $g: \mathbb{R^2} \rightarrow \mathbb{R}$ of class $C^{\infty}$ such that $f(x,y)=xyg(x,y)$ for any $(x,y) \in \mathbb{R}^{2}$. Since $f$ is of class $C^{\infty}$ then all its derivatives are continuous. I don't know how to prove the existence of the function $g$

I'm trying to solve the following exercise  Let $f: \mathbb{R^2} \to \mathbb{R}$ a $C^\infty$ function such that $f(x,0)=f(0,y)=0$ $\forall x,y \in \mathbb{R}$. Then there exists a $C^\infty$ function $g:\mathbb{R^2} \to \mathbb{R}$ satisfying $f(x,y)=xy\, g(x,y)$ $\forall x,y \in \mathbb{R}$  I thought first about expanding $f$ using the taylor theorem, we would have $$f(x,y)=f(0,0)+f'(0,0)(x.y)+\frac{f''(0,0)(x,y)^2}{2!}+r(x,y),$$ but $f(0,0)=0$ and $f_x(0,0)=f_y(0,0)=0$ since $f$ is zero on the $x$ and $y$ axis. $f''(0,0)(x,y)^2=f_{xx}(0,0)x^2+f_{xy}(0,0)xy+f_{yy}(0,0)y^2$, now we have a term that has a product of $x$ and $y$. But I don't know how (and if it is possible) to proceed from here.


This is possibly a stupid question, but one I have been always wondering. What would happen to me if I was in the center of the Large hadron Collider while it was running? Would the energy of the beam cause any short-term or long-term damage?

Some speculation here:   Is there a possibility it would pass 'undetected' through your hand, or is it certain death?  Can you conclude it to be vital, or only loose your hand?  Would it simply make a small cylindrical hole through your hand, or is there some sort of explosion-effect?  Assume your hand has a cross section of 50cm², and a thickness of 2cm, how much of the beam's energy would be transferred to your hand?


When am trying to stop a running thread, most of  the methods to stop the thread are being shown "deprecated" in eclipse. I am using either of the methods stop(),destroy(),suspend(). Is there a new method for stopping a thread?  Thanks.

How do you kill a java.lang.Thread in Java?


When using the shader node editor, I would like to be able to view and edit different materials at the same time.  However, even if I split my view into two sections, both set to view the shader node editor, the views are synchronized. So if I'm initially editing Material 1 in both node editors, I'd like to set the second node editor to Material 2.  But when I do that, both editors change to Material 2. The best I can do is enter a node group in one editor while the other remains at the top level node group. How do I edit two materials simultaneously?

Whenever I open a new shading window, whatever I do in one is just mirrored on the other. If I click a node in one window, the same node and material get selected in the other. I can't edit two shaders at once. How can I edit two shaders simultaneously?


Given $$1\cdot 2^1 + 2\cdot 2^2 + 3\cdot 2^3 + 4\cdot 2^4 + \cdots + d \cdot 2^d = \sum_{r=1}^d r \cdot 2^r,$$ how can we infer to the following solution? $$2 (d-1) \cdot 2^d + 2. $$   Thank you


Chatlet Created Chatlet Thrown Inside reply 5684dc24617149a601dea913 Yes, Please let me in. java.lang.reflect.InvocationTargetException  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)  at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)  at java.lang.reflect.Method.invoke(Unknown Source)  at com.teamchat.client.sdk.impl.TeamchatAPIImpl.invokeMethod(Unknown Source)  at com.teamchat.client.sdk.impl.TeamchatAPIImpl.onMsg(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamConnector.onMsg(Unknown Source)  at com.teamchat.client.sdk.impl.SimpleEventsExecutor.notifyCallbackMessage(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamImpl.handleLine(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamImpl.fetchEventStream(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamImpl.fetchOnceAndReturnInterruptedStatus(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamConnector.getEvents(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamConnector.mainloop(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamConnector.access$000(Unknown Source)  at com.teamchat.client.sdk.events.EventStreamConnector$1.run(Unknown Source)  at java.lang.Thread.run(Unknown Source) Caused by: java.lang.NullPointerException  at frontEnd.sendRequest.onReply(sendRequest.java:75)  ... 16 more     I am currently working on task where I need to throw some message on reading null value from the database cell. But When I try to do so my code throws NullPointerException. I tried to handle it using try catch block but nothing helped me.    public String getCellData(String sql_query) throws Exception {   System.out.println("Inside getCellData");   String cell_data = "";   try{    JSONArray queried_data = (JSONArray)db_work.retrieveQueryRows(db_work.retrieveData(sql_query).toString());    for (int i = 0; i < queried_data.size(); i++) {     JSONArray queried_row=(JSONArray) queried_data.get(i);     cell_data = queried_row.get(0).toString();    }         }   catch(NullPointerException e)   {    cell_data="empty";    return cell_data;   }   return cell_data;  } if(response.equals("Yes, Please let me in.")){    String gender = fetch_details.getCellData("select * from Group_Join where Room='"+room_id+"'");    System.out.println(gender);    String goal = fetch_details.getCellData("select * from Group_Join where Room='"+room_id+"'");    System.out.println(goal);    api.performPostInCurrentRoom(new TextChatlet("Sure, thanks. We will add you to the support group."));    if (goal.equals("empty")) {     if (gender.equals("empty")) {      System.out.println("Gender and Goal Both Empty");      PrimaryChatlet gender_goal_chatlet=new PrimaryChatlet();      gender_goal_chatlet.alias("GenderGoal");      Form gender_goal_form=api.objects().form();      gender_goal_form.addField(api.objects().select().name("Goal").label("Goal").addOption("Weight Loss").addOption("Weight Gain").addOption("Muscle Tone"));      gender_goal_form.addField(api.objects().select().name("Gender").label("Gender").addOption("Male").addOption("Female"));      gender_goal_chatlet.setReplyScreen(gender_goal_form);      api.performPostInCurrentRoom(gender_goal_chatlet);     }

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?


in this C program when i am using  printf("%c",*(name+5));   then program works fine but when i am using   *(name+5) = '#';   then program causes crash  #include <stdio.h> void main(void) {     char * name;     name ="Hello World !";     puts(name);     *(name+5) = '#'; // here is error      puts(name); }

The following code receives seg fault on line 2:  char *str = "string"; str[0] = 'z';  // could be also written as *str = 'z' printf("%s\n", str);   While this works perfectly well:  char str[] = "string"; str[0] = 'z'; printf("%s\n", str);   Tested with MSVC and GCC.


As the title says, if I reset my rooted nexus 4 to factory settings will it be unrooted relocked and superuser uninstalled?

I rooted my Dream/G1 last night and finally gave up on modding it (not for good mind you, but for the moment) and opted instead to just restore it to factory settings via Settings > SD card & phone storage > Factory data reset, which did solve all the problems I was having with multitasking (and not being able to answer it, etc.)  Curiously, I still seem to have root on the phone, despite having reset it. I'd love to understand how that is possible! Superuser Permissions is the only non-stock app still on the phone, and I'm still able to use su to gain root privileges from adb shell. Is this because BusyBox installs to my SD Card?  My phone works just fine, so this is hardly critical, but the whole exercise was/is about knowing my phone better and this is most def. a mystery. Thanks!


I'm having problems calculating this integral.  $$\int\frac{\text{d}x}{\sqrt{\tan(x)}}$$  I don't even know where to begin...  Thanks

I have been having extreme difficulties with this integral. I would appreciate any and all help. $$ \int \sqrt{\tan x} ~ \mathrm{d}{x}. $$


If java is pass by value, then why p1.age is 25 instead of 22? Please provide an explanation. Here is the code: class Person {     Person(String s, int i) {         ++pid;         name=s;         age=i;     }      static int pid;     int age;     String name; }  public class Test {     public static void main(String args[]) {         Person p1 = new Person("John", 22);         Test te = new Test();         Person p2 = te.change(p1);         System.out.println(p2.pid + " " + p2.name + " " + p2.age);         System.out.println(p1.pid + " " + p1.name + " " + p1.age);      }      private Person change(Object o) {         Person p2 = (Person) o;         p2.age = 25;         return p2;     } }   Output :  1 John 25 1 John 25

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


Suppose $G$ is finite, let $A_1,A_2,...,A_n$ be the conjugacy classes in $G$ and they are distinct. how do I show that if $a_ib_j = b_ja_i$ where $a_i$ is in $A_i$ and $b_j$ is in $A_j$, then $G$ is abelian  Thanks

Let $G$ be a finite group and let $g_1 , g_2 ,...,g_r$ be the representatives of its conjugacy classes. If $g_i g_k=g_k g_i$ for every $i,k \in$ {$1,2,...,r$}, then prove that $G$ is abelian.     My original trial was to prove this in arbitrary subgroup of $S_n$ and using Cayley's theorem we can prove this easily, and the reason is we can take advantage of the fact that  if $\tau , \sigma \in S_n$, $$\sigma = (a_{11} ... a_{1 n_{1}})(a_{21} ... a_{2 n_{2}}) ... (a_{r1} ... a_{r  n_{r}})$$  then $$\tau \sigma \tau ^{-1} = (\tau(a_{11}) ... \tau(a_{1 n_{1}}))(\tau(a_{21}) ... \tau(a_{2 n_{2}})) ... (\tau(a_{r1}) ... \tau(a_{r  n_{r}}))$$  But this didn't give me any valuable results, so any hints which can be useful ?  I found a proof of this exercise , but I want to construct my own proof.  Any hints ?


I have asked a few colleagues and none of them knew of one, so I figure Math.SE is probably the best place to ask.  Is there a name for exponentiation repeating $n$ times, like multiplication  is for addition and exponentiation is for multiplication?

We use multiplication for repeated addition, and in turn use exponents for repeated multiplication. What topic comes after this, for repeated exponentials? Is there something my teachers are hiding from me?


I am having real dramas with getting any form of Ubuntu to load onto a server and I'm tearing my hair out... I have a server based on a Commell LV-67K mother board with 8Gb RAM that I am trying to get any install of Ubuntu on to burned through Etcher. The image USB loads fine gets up to the bit where it asks you if you want to try or install etc. you select install it runs its commands and the brings up the Beaver/Panther head screen... and that's it! No window to to continue the installation or anything like that. The ISO works as it should when I run it up through Parallels on my Mac and does all the things it should. I've tried different versions of Ubuntu, different HDD and nothing works...any ideas greatly received!

I have HP G56 laptop and it originally came with Windows 7 which microsoft updated to windows 10 for free. I did clean install and so i don't have option to go back to windows 7.   I want to try Ubuntu as after upgrading to windows 10, my laptop runs slow. I have created bootable USB several times but can't make my laptop to boot. I saw tutorials and already setup bios to boot from USB first and also turnoff fast boot from power option. I can however use other USB for windows 10 that i have and that works but not from Ubuntu USB


Why is it wrong to think that $$\lim_{x \to 0} (1+\tan x)^\frac{1}{x} = (1+0)^\frac{1}{x}=1^\infty=1$$ because $\lim_{x \to 0} \tan x$ and $\lim_{x \to 0} \frac{1}{x}=\infty$? I already know the correct answer but could not figure out why this way is not correct.

From : In calculus and other branches of mathematical analysis, an indeterminate form is an algebraic expression obtained in the context of limits. Limits involving algebraic operations are often performed by replacing subexpressions by their limits; if the expression obtained after this substitution does not give enough information to determine the original limit, it is known as an indeterminate form.    The indeterminate forms include $0^{0},\frac{0}{0},(\infty - \infty),1^{\infty}, \ \text{etc}\cdots$   My question is can anyone give me a nice explanation of why $1^{\infty}$ is considered to be an indeterminate form? Because, i don't see any justification of this fact. I am still perplexed.


NOTE: I'm familiar with this U&L Q&A titled:  that sounds similar to what I'm asking, but there's a subtle difference to what I'm looking for. That one focuses on the process itself detecting that it's in a chrooted environment, I'm asking how one process to find out that another is chrooted.    Was looking into an apache issue in a unfamiliar server. The output of ps -ef looked like this:  [belmin@server131 ~]$ sudo ps -ef | grep httpd apache   14363 4082  0 14:04 ?        00:00:00 /usr/local/apache2/bin/httpd -k start apache   14365 4082  0 14:04 ?        00:00:00 /usr/local/apache2/bin/httpd -k start   I looked in /usr/local/apache2/conf for the configuration and it was not what I expected given the symptoms we were seeing. Decided to double check the init script and noticed the actual process was in a chroot jail.  For future reference, is there a way of figuring out if a process is in a chroot jail with just the PID? And how would I find out the path of the chroot jail?

I have a unix installation that's supposed to be usable both as a chroot and as a standalone system. If it's running as a chroot, I don't want to run any service (cron, inetd, and so on), because they would conflict with the host system or be redundant.  How do I write a shell script that behaves differently depending on whether it's running in a chroot? My immediate need is a modern Linux system, with /proc mounted in the chroot, and the script is running as root, but more portable answers are welcome as well. (See  for the case of Linux without /proc.)  More generally, suggestions that work for other containment methods would be interesting. The practical question is, is this system supposed to be running any services? (The answer being no in a chroot, and yes in a full-fledged virtual machines; I don't know about intermediate cases such as jails or containers.)


Not sure what I've done or pressed, but in edit mode if I select a vertex/edge/face the whole mesh is transformed when I grab, rotate, etc. Also if I add new mesh elements and scale for instance even unselected elements are scaling  What have I pressed?  Thanks John

My problem is that I sometimes lose the ability to independently translate or otherwise transform any parts of a single mesh. If I try, for example, to just translate several faces, edges, or vertices, then the entire mesh will stretch and displace itself in order to follow the translation. Or, alternatively, if I try to translate just one face then the whole mesh will move as if I'm translating in Object Mode.  I'm not really sure I know how to describe this problem properly. I don't even know how to reliably reproduce it. It seems to happen to any given mesh at random, and it doesn't stop happening to that mesh unless I delete and remake it.  I assume that I must be doing something wrong to cause this to happen. Does anyone have any ideas? Thanks.


I have dd crashing after running a few hours.  Typically with a message like  Input/output error 68424+1 records in 68424+1 records out 342124883968 bytes (342 GB) copied, 5114.68 s, 66.9 MB/s   Is there something I can do about it?  Is there some way I can use the output? Or restart where it left off?  Is there any reason to think it is because the partition being backed up is being used?  It always crashes around 70-80%, often when the partition should be less-used.  Since this process takes so long, it is difficult to try different things.  I output to an image.  I could probably use a partition, but LVM is involved:  sudo lvmdiskscan /dev/centos/swap [       3.89 GiB]  /dev/sda1        [     500.00 MiB]  /dev/centos/root [      50.00 GiB]  /dev/sda2        [     465.27 GiB] LVM physical volume /dev/centos/home [     411.38 GiB]  /dev/sdb1        [     931.51 GiB]  3 disks 2 partitions 0 LVM physical volume whole disks 1 LVM physical volume   dd conv=sync,noerror if=/dev/centos/home bs=2000000   of=/run/media/ob/X_1T_Media1GHD-PCTU3/c/sd9e22_cel.image dd: error reading '/dev/centos/home': Input/output error 171062+1 records in 171063+0 records out 342126000000 bytes (342 GB) copied, 4625.3 s, 74.0 MB/s 220856+2 records in 220858+0 records out 441716000000 bytes (442 GB) copied, 6138.1 s, 72.0 MB/s   Friday Morning  ddrescue --sector-size=2048 --cluster-size=$((256*512)) --sparse --verbose /dev/centos/home /run/media/ob/X_1T_Media1GHD-PCTU3/c/sd7c_dd.image /run/media/ob/X_1T_Media1GHD-PCTU3/c/sd7c_dd.map  GNU ddrescue 1.18.1 About to copy 441714 MBytes from /dev/centos/home to /run/media/ob/X_1T_Media1GHD-PCTU3/c/sd7c_dd.image     Starting positions: infile = 0 B,  outfile = 0 B     Copy block size: 131072 sectors       Initial skip size: 32 sectors Sector size: 2048 Bytes  Press Ctrl-C to interrupt rescued:   441714 MB,  errsize:    8192 B,  current rate:        0 B/s    ipos:   342124 MB,   errors:       1,    average rate:   60675 kB/s    opos:   342124 MB, run time:    2.02 h,  successful read:       9 s ago Finished    But   extundelete sd7c_dd.image  --restore-directory /home/ob/p -o /tmp/tt extundelete: Bad magic number in super-block when trying to open filesystem sd7c_dd.image   /dev/mapper/centos-home on /home type xfs (rw,relatime,attr2,inode64,noquota)

How do I backup a LVM partition to an image for recovery purposes?  I am trying to run dd on /dev/sda2, but it crashes after ca 8 hours, at around 380G   sudo lvmdiskscan   /dev/centos/swap [       3.89 GiB]    /dev/sda1        [     500.00 MiB]    /dev/centos/root [      50.00 GiB]    /dev/sda2        [     465.27 GiB] LVM physical volume   /dev/centos/home [     411.38 GiB]    /dev/sdb1        [     931.51 GiB]    3 disks   2 partitions   0 LVM physical volume whole disks   1 LVM physical volume   Anyway, could running from a stick make any difference?


I am studying bitwise operations in bash and understand all the other operations, but this one. It will be a great help if someone can explain (with examples) what the negation (~) operator does in bitwise operations. Couldn't understand from what I read here and elsewhere. TIA!

$ echo $(( 255 )) 255 $ echo $(( 33 )) 33 $ echo $(( ~33 )) -34 $ echo $(( ~255 )) -256 $    and my kernel is:  $ uname -a Linux HOSTNAME 3.2.0-40-generic-pae #64-Ubuntu SMP Mon Mar 25 21:44:41 UTC 2013 i686 i686 i386 GNU/Linux     QUESTION: ~ is for negating the number AFAIK. But why does ~33 produce -34 and why does ~255 produce -256?


Consider the following isosceles triangle (not drawn to scale)                                 where $\alpha=70^\circ$, $\beta=10^\circ$, $\gamma=20^\circ$ and $\delta=60^\circ$. Find $x$.  A friend gave me this problem a few weeks ago and the only hint I was given was to use elementary geometry, such as the sum of the interior angles of a triangle equals $180^\circ$. I concluded that I eventually need to draw extra lines and possibly deduce something from similar triangles, but so far I haven't figured out much. Any ideas? Am I missing some result that is crucial to the proof?

I've been solving this for days but I still I couldn't solve this. Can I know how to solve $x$ ?


I'm trying to verify the solution of St.Peterburg paradox:  when W = c = 2.  $$\sum_{t=1}^{\infty}2^{-t}\left(\ln\left(W+2^{t-1}-c\right)-\ln W\right)=0$$  In terms of math, I need to check if the LHS of the expression above equals to 0 when W=c=2.  $$\Leftrightarrow\sum_{t=1}^{\infty}2^{-t}\left(\left(t-1\right)\ln2-\ln2\right)=0\Leftrightarrow$$  $$\Leftrightarrow\sum_{t=1}^{\infty}2^{-t}\left(t-2\right)\ln2=0\Leftrightarrow\sum_{t=1}^{\infty}2^{-t}\left(t-2\right)=0\Leftrightarrow\sum_{t=1}^{\infty}\frac{t}{2^{t}}-2\sum_{t=1}^{\infty}\frac{1}{2^{t}}=0\Leftrightarrow$$  $$\Leftrightarrow\sum_{t=1}^{\infty}\frac{t}{2^{t}}-2\left(\frac{0.5}{1-0.5}\right)=0\Leftrightarrow\sum_{t=1}^{\infty}\frac{t}{2^{t}}=2$$  How to prove, assuming that I didn't make a mistake previously, that $\sum_{t=1}^{\infty}\frac{t}{2^{t}}=2$.

How can I evaluate $$\sum_{n=1}^\infty\frac{2n}{3^{n+1}}$$? I know the answer thanks to , but I'm more concerned with how I can derive that answer. It cites tests to prove that it is convergent, but my class has never learned these before. So I feel that there must be a simpler method.  In general, how can I evaluate $$\sum_{n=0}^\infty (n+1)x^n?$$


With Blender 3D, can I print a custom size color graphic of the model? I want to print 20 x 30 inches in high definition.

Is there a way to output for Print. I want to save in a higher DPI than the default 72dpi say 300dpi that's a good quality for printed pieces. I tried downloading an add-on but don't know if I am installing it correctly it isn't showing up but the bar in python is green. I'm using the 2.69 version of Blender. If no such feature exists what size have any of you found best for print quality. Thank you


Let's say I have a variable that could represent a number of different models (Objects). I want to respond to each differently, ideally through a switch statement. Is it possible to get the instanceof result as a value?  For example, something like this:  function determineModel(model) {     switch (model instanceof) {  // this does not work         case 'Foo':             // do something             break;         case 'Bar':             // do something else             break;         default:     } }

Is there a JavaScript equivalent of Java's class.getName()?


There have been a lot of updates since the last answered question on this topic, including removal of the chrome toolbox from the extension site.  While I have been able to, for some time, continue to have my tabs scroll by manually porting chrome toolbox and enabling it.  However, recently this method has stopped working.  I would rather not have to bind the ctrl+tab and ctrl+shift+tab to my mouse up/down as it would not allow me to scroll when over the page itself.  I know one of the reasons that this was removed was that it interferes with youtube playback somehow, but I rarely use youtube and this functionality is more important to me.  Is there any current and reputable extensions that will provide this functionality?  Is there a way to enable and/or modify the browser myself in order to achieve this?

At home I'm running Fedora 17, and I've grown accustomed to quickly scanning through open tabs by using the mouse wheel while hovering over the tab bar. It's a very natural gesture for me now.  At least once a week at work (usually Mondays), I attempt to use the same technique on chrome running on a MacBook Pro, but the tabs won't budge. This is starting to make me crazy.  Does anyone have a solution which will allow me to use the scroll wheel to change tabs on google chrome for OSX?  (I found the following google code thread, but the suggested fix does not address the issue as far as I can tell -- )


I've read a bit about the reason for using the double possessive but there are still a few aspects that don't work for me:  If the difference between "Joe is a friend of Jim's" and "Joe is a friend of Jim" is the active person (with Jim being active in the first sentence and Joe in the second) then the sentence "Joe is a friend of Jim's" should have the same meaning as "Joe is Jim's friend," and the sentence "Joe is a friend of Jim" should have the same meaning as "Jim is Joe's friend."  Using the same logic, the sentence "Joe is my friend" should have the same meaning as "Joe is a friend of mine" and the sentence "I am Joe's friend" should have  the same meaning as "Joe is a friend of me," which we would never say.  Furthermore, one would never say "Jesus is the son of the Lord's" when they mean "Jesus is the Lord's son;"  rather one would say, "Jesus is the son of the Lord."  If the difference between the two is that "Joe is a friend of Jim's" implies that Jim has multiple friends while "Joe is a friend of Jim" does not, then the same issue arises when I try to say "Joe is a friend of mine" without implying that I have multiple friends I say "Joe is a friend of me" which, again, one would never say.  Also, you wouldn't say "Jim is an owner of the club's" when you mean "Jim is one of the club's owners."  If two conditions must apply, that is the double possessive can be used only if the word after of refers to an animate object and the word before of involves only a portion of the animate object's possessions, I still can't say "Joe is a friend of me" if Joe is my only friend or "Jim is a friend of him" if Jim is his only friend.  Also, can't one say "Joe is the only friend of Jim's?"  Also, I don't want to hear that the second apostrophe is the only way to distinguish between "a picture of the king" and "a picture of the king's."  In the sentence "a picture of the king" the of is not a possessive; you can't say "the picture of the king's."

As  shows, we nearly always use the possessive form of personal pronouns for friend of mine/his/ours/etc.  But when it comes to actual names, we prefer  without the possessive apostrophe. That preference is even more marked with, say, . Not that I think the usage itself is particularly American - it's much the same with .  Personally, I find friend of him grates. In general I've no strong feelings either way as to whether it's friend of Peter or friend of Peter's (though I deplore the possessive in ), but in line with many others, I really don't like the possessive in relation to things like countries.  Why is this?   Edit: Noting an apparent "progression" (pronoun -> person -> nation) marked by reduction in use of the possessive, I checked at a finer "granularity". NGram shows that although it does occur,  virtually "flatlines" against friend of mine. But the bias reduces through of you, of us, and by the time I get to  it's much less extreme. There seems to be something "egocentric" about the double possessive.  Presumably when babies learn to speak, they soon notice that possessive pronouns, possessive apostrophes, and the word "of", all do the same job. Parents would correct a child who says "of mine's", but probably wouldn't even notice the same "redundancy" in "of Peter's". Younger speakers are unlikely to even be talking about something "of America's". Perhaps as we mature we tend to discard the "double possessive" for the more "distant" things that only adults are likely talk about, but we keep it for "closer" people because that's how we spoke when we were younger.  EDIT2 I note that I'm a great fan of him is vanishingly rare compared to ...fan of his, but with ...fan (of John) the double possessive occurs far less often than ...friend (of John's). Usage seems to be affected by the noun before "of" as well as the one after it. This is getting complicated...


Is there any notion of taking a continuous product of the values of a real function over an interval? Only thing I could think of was exponentiating to the power of the integral over that interval.

Addition is to Integration as Multiplication is to ______ ? Everyone knows that definite integration  is "a way to sum continuum-many terms" in a rough sense. Can we "multiply continuum-many factors"  in a similar sense?


I want to install v4l-utils, actually, I'm Using L4T on TX2.  A few days ago, I updated L4T version 27.1 -> 28.1.  And then I couln't open System Settings -> Software & Updates.  Anyway, I ran sudo apt-get install v4l-utils but an error occurred:  E: Unable to locate package v4l-utils.   I tried to find other articles like  in order to fix this, but my case seems a little different.  In conclusion, I have two problems.   I can't install v4l-utils. I can't open Software & Updates.

When I try to install any package through the command line, I get an error.   $ sudo apt-get install <package> Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package <package>   Can anyone help me on this?


I've been working on some modals for an app, and I have done some research into how various confirmation/abort options are presented to the user in the footer of a modal.   posted a nice shot with this treatment for his buttons:    I've seen this treatment before, where the "abort" option isn't actually a button, but never read any sort of reasoning or justification behind it. Could anyone give me some justification? I seem to prefer this method, but that's not enough of a reason to style it that way.  My assumption is that the user has intentionally taken some actions to get this modal, so the option to complete the full action is more prominently displayed than an exit (in case they made a mistake).  Extra points for a link to a study or discussion.

I understand the idea behind having the more likely to be used action on a page slightly larger or in a different style in order to guide the user to it (for example having a button for save but a small text link for cancel).  When say an administrator hits delete I have a confirmation dialog appearing asking if they are sure they want to do that and presenting them with two options, 'Yes, Delete this' and 'No, Keep this'.  At the moment these are the same size and style and therefore the same weight on the page.  I was wondering if that should be the case or should I assume that the administrator is not an idiot and that if they have hit delete confirming this action is the most important part of his next step and therefore should be given a greater weighting on the page?


I think I saw the inequality $$|\sin x-\sin y|\le |x-y|$$ somewhere recently.  I've been trying to see why it could be true but so far have been unable to come up with any success.  Could someone show a way to prove this?  Thanks.  PS. Intuitively, this seems to make sense since an arc is always bigger than its sine in magnitude. But how to show this rigorously?

Show that  $$\left | \sin a - \sin b \right | \leq \left | a-b \right |$$  I saw a proof using The Mean Value Theorem, but I could not grasp it well. Are there any other proofs or can someone clarify it by using The Mean Value Theorem?


I am having installation problem on Asus K55VD laptop.I selected Install Ubuntu alongside Windows 8 and after clicking to Continue it restarts my laptop and I cannot install Ubuntu.

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


What does it mean by automatically lifted?    The ban will be lifted automatically by the system when it determines that your positive contributions outweigh the cost of those questions which were poorly received.  I am a software engineer so I doubt that the system itself can actually evaluate the updates to the questions. It probably requires input from humans.   Do people regularly look at closed questions and re-evaluate them? It seems to me that once a question is closed there is a strong bias against reopening it, thus being blocked from asking questions is hopeless.   I have a high reputation (top 10% for the year) and I thought this would prevent question bans so I had no idea that I had to be very careful about asking questions.   If I knew this I would have asked some easy questions to get my question reputation up before I asked the very difficult ones. Stack Exchange doesn't seem to be very good at communicating this crucial information.     I don't think that this is a duplicate because I was originally thinking that artificial intelligence might examine the questions. That people look at the questions and that the questions are put to the top of the home page so that they can be reviewed were two aspects that may be unique to this question.   When referring to the other post it says that the ban will be lifted from other positive contributions. I currently have a reputation that is in the top 10% for the year why is that not enough positive contributions?

I asked a couple of really bad (horrible!) questions here and got hit with a question ban. No surprise there – I was a new user, and now know where I went wrong. The problem is that I can't get question privileges back. The bad questions were bad enough that I don't think I could've edited them to be better – it wasn't formatting or style – the questions themselves were just bad questions, so I deleted them.   The  said that my question privileges would automatically be reinstated once my "positive contributions" outweighed my negative ones. I realize that it's done automatically, but as an extremely new coder, I really can't do much in the way of positive contributions except upvotes (if that can even be considered a contribution). What should I do to lift the ban?


Here's a quick backstory as to why I'm making this post. If you don't want to read it, skip to the bold. I've just recently picked up Minecraft after a couple years and started playing around with it. After I got comfortable messing around with it, I noticed that they implemented command blocks into the game and I wanted to see if I remembered how to use them. I messed around with command blocks for a while before I wanted to give myself a weapon. I did a little bit of research on command blocks, tried several different commands, but nothing can get me what I want. So I thought to ask you guys, after all, some of the commands I tried were on here. This is where you start reading I want a netherite sword with the title >The Legendary Sword of Power< (How original) and the lore being >The Ancient Ones used this weapon to kill the powerful Wither.< On top of that, I wanted to give it a couple overpowered enchantments. If anyone could help me with this (or just give me a command), that would be highly appreciated. Thank you!

I'm used to creating Java Edition Minecraft maps, where NBT can be used to set many different block, item, and entity properties, like an item's CanPlaceOn/CanDestroy list, a chest's items, and more! To open my maps up to more players, I've started creating maps on Minecraft Bedrock Edition as well. But NBT is inaccessible from commands in BE, which I knew before, but didn't know how much of a problem I would have creating these complicated command chains. One of the things that I've always been doing is giving players items with custom item names, lores, enchantments, and other properties. But there is a problem. All this would have been done in NBT in Java Edition. In Bedrock, NBT is inaccessible from commands, meaning the commands I used in JE don't work. Are my dreams crushed?


Recently I've bought an inkjet printer HP Deskjet 1010 for my personal use. I've some problem with it. On which Stack Exchange site should I ask the question about my printer?

There seems to be more than a few computer science/programming Stack Exchange networks (is that the correct term?). Stack Overflow, being the first, has by far the most users, questions, and answers.  What is the reasoning for creating the others, and are there clear guidelines for which kinds of questions should be posted? I can see a large amount of potential overflow, many cases of people not getting a good answer to their question, because the person who has the answer isn't browsing that particular network at the moment.  I understand that they were probably created for organizational purposes, but wouldn't it almost make more sense to just have them as categories under Stack Overflow, keep them separated but still connected, instead of making people have to create multiple 'account's, one for each network?  I am sure there was a very good reason to break them up, but as someone that is new to SE, it can be somewhat intimidating to decide which one to post in to ensure you get a good answer. For example, if I am a computer science student, my first instinct might to be to post in the computer science network, until I see that it literally has 1% of the users as the Stack Overflow network, which still seems to be for programming/computer science related questions.  So my second instinct would then to be to post it into the Stack Overflow site on the basis that I have a significantly higher chance of my question being seen and getting a good answer. Then I notice that there is also a 'programmers' network, and I don't even begin to know where that fits in. I, and I am assuming most people, will probably just post on Stack Overflow to be safe.  My question is, other than the short little description blurb of each one, is there a clear cut set of guidelines which what each network is intended for, what kinds of questions should go to each one, and is anything being done to encourage people to post in these newer, smaller (more specialized?) networks as opposed to just posting in big daddy Stack Overflow?  Now again, this is for computer science/programming/"why isn't this code doing what I want?" related questions, I am not saying that if I had a question about Linux or WordPress or something I would have the same confusion.


Let A = K[x,y,z] and let p be the ideal ($xz - y^2, yz - x^3, x^2y - z^2$). Is $p^2$ a $p$-primary ideal?   I'm still trying to get used to the idea of p-primary modules and I am having some trouble with this example.   From what I understand, p$^2$ will be p-primary if and only if for every $a \in$ p, the map $A/{p^2} \rightarrow A/{p^2}$ given by multiplication by $a$ is injective if $a \notin p$ and nilpotent if $a \in p$.  Here the ring $A/p^2 = $ $\frac{K[x,y,z]}{((xz - y^2)^2,(yz - x^3)^2,(x^2y - z^2)^2, (xz - y^2)(yz - x^3),(xz - y^2)(x^2y - z^2),(yz - x^3)  )(x^2y - z^2))}$  It may or may not be reasonable to make this simpler since basically two of the three polynomials must be zero and the sqaure of the third must be zero. But regardless, I don't see why this map should be injective / nilpotent at for the appropriate multiplication. (Or if p$^2$ is not p-primary, then I don't see any counterexample or why this should be the case).  Aside: This is an unrelated question, but I was trying to show that p is a prime ideal and I believe that it is the kenel of the m

The question may have been addressed in Math SE before; but my question is a little variation of it, coming because of a very common example for this question.  It is well known that powers of a prime ideal need not be primary and a standard example is to consider the quotient of $k[x,y,z]$ by the ideal $(xy-z^2)$, and in the quotient ring, take the prime ideal $(\bar{x},\bar{z})$; its square is not primary.  Now this example of prime ideal is in quotient of polynomial ring.   Q. Can we construct an example of a prime ideal within a polynomial ring, say $k[x,y]$ or $k[x,y,z]$, whose some power is not primary?


I'm struggling with the following sentence in an APA format paper. I don't like the double usage of and here, but 'supply and demand' is one thing in this context. Is this correct or do I need to make a change?     Riggs (2011) argues that tuition prices can be explained by the basic principles of supply and demand and perceived quality.   To clarify: My intent is for the term "basic principles" to apply to both "supply and demand" (as a single principle) and "perceived quality" as the other. As this sentence is paraphrasing Riggs, this must be the meaning conveyed whether or not we agree with his over-simplification of S&D.

For example,      I like chocolate, vanilla, and lemon and orange ice cream.    Indicating "lemon and orange" is a combined flavor, as an item in the list needing an initial and.


I recently discoverd that the current moves from the negative to postivie, but if I placed a diode from postivive to negative it will work, but if I placed it the wrong way (from negative to positive, like how the current moves) it won't work.

Im having a bit of trouble drawing a circuit with a diode in. I know the current flows from negative to positive, but convention says that current goes from positive to negative.  When drawing a circuit with a diode do you draw the arrow pointing to the positive (matching the actual flow of electrons) or towards the negative terminal (matching conventional current)?  If you follow convention then surely when building circuits from the diagram the diode will not allow current as it is actually facing the incorrect way?


Every finite commutative ring $R$ must be of the form $\frac{ \mathbb{Z} }{n_1 \mathbb{Z}} \times \frac{\mathbb{Z}}{n_2 \mathbb{Z}} \times \dots \frac{\mathbb{Z}}{n_k \mathbb{Z}}$. I am unable to find a counterexample. I heard that a field of order $4$ works, but I cannot see the reason. Can anyone explain why a field of order $4$ cannot be of the form above.

Every finite commutative ring $R$ must be of the form $\frac{ \mathbb{Z} }{n_1 \mathbb{Z}} \times \frac{\mathbb{Z}}{n_2 \mathbb{Z}} \times \dots \frac{\mathbb{Z}}{n_k \mathbb{Z}}$. I am able to proceed upto the step that it should be direct product of artinian commutative local rings. I used structure theorem for commutative ring. But I am unable to proceed further.


The Schwarzschild solution of Einstein's field equations clearly shows that a far away observer sees time slow down for an in-falling object. Relative to him, it takes an infinite amount of time for the object to reach the event horizon. But all black holes evaporate by Hawking radiation in a long but finite time. So wouldn't the observer see the BH completely evaporate away before any object reaches its event horizon?   What would an in-falling person experience? In a very short finite proper time, he would expect to reach the event horizon. But since the BH lost mass, the event horizon would have shrunk. It would keep shrinking away from him, until its radius is zero and the BH is gone. Would he see an explosion at this time and then be in free space in the far future?   Considering time dilation of particles collapsing to form a BH, it seems that neither an event horizon or singularity could ever form in a finite time. Astronomical BHs would really be concentric shells of matter that have almost, but not quite, shrunk within their Schwarzschild radius. Does this seem reasonable?

I am not a professional physicist, so I may say something rubbish in here, but this question has always popped in my mind every time I read or hear anyone speak of particles hitting singularities and "weird things happen".   Now to the question at hand, please follow my slow reasoning... As far as I've learned, to reach a black hole singularity, you must first cross an event horizon. The event horizon has this particular property of putting the external universe on an infinite speed to the falling observer. Now due to the Hawking radiation, and knowing that the cosmic background radiation is slowly dimming, sooner or later every black hole in this particular instance of inflation we are living in will evaporate, according to an external observer of said black holes.  This means that every black hole has a finite timespan, as long as this universe survives that long. Now if we go back to the falling observer, we had already established that such an observer would see the outside universe "speed up" infinitely. This means that when the falling observer "hits" the event horizon, he will (or it if we speak about particles, which is clearer in this case), be immediately transported in time towards the final evaporation moment of the black hole. Either this or the particle gets some weird treatment. My point is, such a particle never gets to the singularity, because it has no time to get to it. The moment it crosses the event horizon, the black hole itself evaporates.  Where am I wrong here?


After the quest "Hard Answers", Karliah told me to meet her at the Ragged Flagon, but it never came up in my journal or even came up as a quest.   I go to meet her at the Ragged Flagon and she isn't there. Tried going back to the Sanctum where we first met and she was there, trapped behind a door. I opened the door to free her and tried talking again but she doesn't say anything. I tried going back to the Ragged Flagon again but she still is not there.

During the 'Hard Answers' Thieves Guild quest, Karliah asked me to meet her at the Ragged Flagon.  However, it seems that she doesn't show up at the rendezvous point.  Where do I find her?


iTunes won't load. Error: iTunes can’t verify the identity of the server “init.itunes.apple.com”.

Prior to the  my system was working fine. After that, I'm getting invalid certificates everywhere:   iTunes says "iTunes can’t verify the identity of the server “init.itunes.apple.com”." and "iTunes can’t verify the identity of the server “xp.apple.com”." when I open it. Chrome gives me warnings for many https sites (e.g. Google is fine, Twitter isn't). Most importantly I can't connect to the App Store anymore, which I was planning to do to upgrade to Yosemite given that Apple decided to not fix one of the security vulnerabilities for the previous versions.   I checked my certificates in the Keychain Access and I don't see anything wrong with them. I've also tried deleting some files related to certificate caches as I've seen mentioned somewhere else, but it didn't help either.  I'm using OS X 10.9.5 in a MacBook Air, Late 2012.  Update  This problem also applies to some systems updated from OS X 10.10 Yosemite to OS X 10.11.1 (15B42) El Capitan.


I have CSGO installed in my MacBook and I don't want to re-download at least the whole file. So I was thinking if it is possible to create a steam backup on my MacBook and restore the file on steam PC or by copying files from PC?  Is it possible for at least some file?

I have a very slow Internet connection at home and cannot download large files there. However, I have a Macbook and fast Internet at school. Is it possible to download a game to my Macbook, then transfer the files to my home PC? Are the files different for Macs and PCs?  I did see  about general Steam file transfer from PC to PC, but it says nothing about Macs. I wasn't sure if the files are the same or not.  Edit: I just found  and it sounds like a direct download isn't possible, but maybe saving a few gigs of data by copying asset files would work.


Construct an infinitely differentiable function which is identically 0 on the intervals $[0, 1]$, $[4, 5]$, and is identically 1 on the intervals $[2, 3]$ and $[6, 7]$.

It is easily shown that the function $$\begin{cases} \exp \left(\frac{1}{x^2-1} \right) & |x| < 1 \\ 0 & \text{otherwise} \\ \end{cases}$$ is smooth and has compact support in $\mathbb R$. I tried playing with it to find a function with the following properties:  a. $f(x)=0$ for $x \le 0$  b. $f(x)=1$ for $x \ge 1$  c. $f$ is monotonically increasing.  d. $f$ is smooth.  Is it possible to find an explicit formula for such $f$?


Having this confusion with react-native (javascript) function declaration  _onclick = (resp) => { //some functions }   and,  _onclick(resp){ //some functions }   what is the difference between both declarations? or they are actually the same?

I've recently started maintaining someone else's JavaScript code. I'm fixing bugs, adding features and also trying to tidy up the code and make it more consistent.  The previous developer used two ways of declaring functions and I can't work out if there is a reason behind it or not.  The two ways are:  var functionOne = function() {     // Some code };     function functionTwo() {     // Some code }   What are the reasons for using these two different methods and what are the pros and cons of each? Is there anything that can be done with one method that can't be done with the other?


Show that every prime $p>3$ is either of the form $6n+1$ or of the form $6n+5$, where $n=0,1,2, \dots$

Is that true that all the prime numbers are of the form $6m \pm 1$ ?  If so, can you please provide an example?  Thanks in advance.


I am currently studying electrodynamics with all the fields and the like. Now, as I understand it, in a more modern viewpoint there is a duality between electromagnetic fields and photons, with photons being the particles that are exchanged in the process of interaction.  My question is, what is the current explanation to what an electromagnetic field is? For example, consider a point charge $q_1$. In order for another charge $q_2$ to 'feel' $q_1$, there is an electromagnetic field generated by $q_1$ that allows interaction. However, using the photon picture of view, a charge should then constantly radiate photons in all possible directions to let other charges know that it's here and should be interacted with. This leads to a problem in energy conservation, as each photon carries an energy $h\nu$, and thus even if a charge is at rest it would radiate off its energy and subsequently be gone.  How can this be resolved? What is the real connection between an electromagnetic field and photons?

I continue to find it amazing that something as “bulky” and macroscopic as a static magnetic or electric field is actually a manifestation of virtual photons.  So putting on your QFT spectacles, look closely at the space near the pole of a powerful magnet – virtual photons! Now look between the plates of a charged capacitor – virtual photons again!   But if it’s all virtual photons, how do we get the difference between a magnetic and electric field?  [This question needs the tag "magnetostatics" as well].


I am a beginner in blender and I made a cylinder mesh then I went into the edit mode to scale only the base loop but everytime I try, it scales the entire mesh. I tried selecting only vertices or edges and both of them together but it made no difference. What am I doing wrong?

My problem is that I sometimes lose the ability to independently translate or otherwise transform any parts of a single mesh. If I try, for example, to just translate several faces, edges, or vertices, then the entire mesh will stretch and displace itself in order to follow the translation. Or, alternatively, if I try to translate just one face then the whole mesh will move as if I'm translating in Object Mode.  I'm not really sure I know how to describe this problem properly. I don't even know how to reliably reproduce it. It seems to happen to any given mesh at random, and it doesn't stop happening to that mesh unless I delete and remake it.  I assume that I must be doing something wrong to cause this to happen. Does anyone have any ideas? Thanks.


It is well known that $\sum\limits_{n=0}^\infty \frac{x^n}{(n!)} = e^x$. What is $\sum\limits_{n=0}^\infty \frac{x^n}{(n!)^2}$ ?

Does the following series have a closed-form expression:  $$\sum_{k=0}^{\infty} \frac{z^k}{(k!)^2}$$  I know that it must converge because:  $$\sum_{k=0}^{\infty} \frac{z^k}{k!} = e^z$$  and the $(k!)^2$ denominator obviously increases more quickly than the $k!$ denominator.  This problem came up in computing the probability of a draw in a football match with each team's goal scoring modeled as a Poisson process.  Thanks,  John


I'm trying to check if a jquery object is null  to use it this way  var reminder_history_div = $(".history-container");         if(reminder_history_div)             reminder_history_div.scrollTop(reminder_history_div[0].scrollHeight);   but reminder_history_div is not null or empty its and object ,with some info ,what is the correct way to check if is empty?maybe:  if(reminder_history_div.length > 0)

How can I check the existence of an element in jQuery?  The current code that I have is this:  if ($(selector).length > 0) {     // Do something }   Is there a more elegant way to approach this? Perhaps a plugin or a function?


I look forward to getting first-hand insights and behind-the-scene perspectives from XXX’s professors  who are thought leaders and experts in their fields.   Should I replace to getting with to get ?  I checked on other forums regarding to + -ING vs infinitive form, but I didn't find a satisfactory answer.     The to getting doesn't seem correct while speaking.

I often see constructions like this one:     I look forward to hearing from you soon.   It seems a little strange to me. In my mind it would look better using the infinitive form "to hear". I don't know if it has something with the verbals... Anyway, what I want to know is which form is correct and why?


I a have a small problem with Git commit. So I am working on some project and using Git. I did a Git commit and I accidentally wrote a wrong commit message. So my question is:     Is there anyway I can change the commit message in Git?   NOTE: I have tried to do this way:  git commit -a --amend -m "New Commit Message"   But it doesn't work. Why?  Thanks.

I wrote the wrong thing in a commit message.  How can I change the message? The commit has not been pushed yet.


I have a mass sliding down an inclined plane. I am changing the angle of inclination at intervals of 10 degrees starting from 10 till 80 degrees. Will the kinetic friction be the same for all angles or will it reduce as the angle gets closer yo 90 degrees?

The coefficient of kinetic friction can be calculated using $\mu_k = F_k/F_n$. A change in angle does not affect the normal force, but doesn't a change in angle affect the friction? As in if the angle is steeper, wouldn't the object have a greater propensity to move down the slope, thus there will be less friction?


Earlier today I asked a , seeking to clarify whether Stack Exchange (the commercial organisation) subscribes to a particular pseudo-scientific idea or not.  There ensued an animated, albeit entirely civil, discussion.   Some people supported subscribing to the idea, regardless of SE's perspective Some people opposed subscribing to the idea, regardless of SE's perspective Some people speculated that SE probably subscribed to the idea Some people felt the question was ambiguous Many people thought the question worth downvoting Many other people thought the question worth upvoting   Certainly there was no unanimity, but there definitely was no shortage of intelligent exchange. Between humans.  Then Community♦ came along.  Community♦ deleted the question and said:     This question was deleted as spam or offensive   I don't think the question was either spam or offensive.  I'm fairly certain that many others, whichever position above they took, also did not consider the question spam or offensive.  Is there any way to appeal a Community♦ judgement? Or is the judgement final?

When flagging, there are two special case options: spam and rude or abusive.   What is spam, and when should I flag content as such? What is considered offensive, rude or abusive content? How does the spam flag differ from the rude or abusive flag? What is the effect of these special flags? When are these flags removed?


Say you have an unfair 3-sided die. Side 1 will be rolled with probability $p_1$. Side 2 will be rolled with probability $p_2$. Side 3 will be rolled with probability $p_3$. Find a formula for the probability that the 8th 3 will be rolled on the 10th roll.  My theory on this is to use a binomial distribution, but I am pretty lost. Could anyone with more experience in probability help me out with this? I was just trying to work through a book I had and I want to figure this out. Edit: Using Robert's advice this is the direction I'm going: $9\choose 7$$(p_3)^7$$(1-p_3)^2*p_3$ Any advice?

An unfair three-sided die. Side $1$ will be rolled with probability $p_1$ , Side $2$ with probability $p_ 2$ and Side $3$ with probability $p_ 3$ . Find a formula for the probability that the $8^{th}$ $3$ will be rolled on the $10^{th}$ roll.  Attempt:  First 9 rolls there are 7 three's.  $$[\binom{9}{7}(p_3)^7(p_1+p_2)^2]\cdot p_3$$ $$=[84\cdot(p_3)^7(p_1+p_2)^2]\cdot p_3$$  any thoughts of this solution?


Why when $A\in M_n(F)$ where $F$ is a field then $A^n=0$ if $A^k=0$ for some integer $k$?

Let $A$ be an $n \times n$ matrix over a field $k$. Or, more generally, an endomorphism of an $n$-dimensional $k$-vector space. Then the minimal polynomial $p_A(t)$, of $A$, has degree at most $n$. The usual way to show this is as a corollary of Cayley-Hamilton:     If $\Phi_A(t) = \det(tI - A)$ then $\Phi_A(A) = 0$ and $\deg \Phi_A = n$. Since $p_A \mid \Phi_A$, it follows that $\deg p_A \le n$.   One can also prove this using the structure theorem:     The $k[t]$-module $V = k^n$, with action given by $t \cdot v = Av$, decomposes as a direct sum $$V \cong \bigoplus_{i = 1}^r k[t]/(q_i), $$ where $0 \ne q_1 \mid q_2 \mid \dots \mid q_r = p_A$. Taking dimensions we have $$ n = \sum_{i = 1}^r \deg q_i. $$ Therefore $\deg p_A = \deg q_r \le n$.   It is clear that we do not need the full strength of the structure theorem; all we need to do is show that there is a module-embedding $$ k[t]/(p_A) \hookrightarrow V. $$ This is shown in the course of proving the structure theorem.  Question:  Can we show that $\deg p_A \le \dim V$ without using Cayley-Hamilton or the the structure theorem? In particular, are there any easier proofs of this fact than as a corollary of Cayley-Hamilton?


Let $p_1 = 4$, $p_2 = 8$, and $p_n = 6p_{n−1} − 4p_{n−2}$ for each integer $n ≥ 3$.   Prove by strong induction that $2^n$ divides $p_n$ for all integers $n ≥ 1$   I got up to the base step where by you prove for $p_3$ but unsure about the strong induction step

Provided the following sequence of integers $t_1, t_2, t_3$,... is defined as:    $t_1 =4, t_2 =8$ and $t_n= $ $ 6t_n$$_-$$_1$ - $4t_n$$_-$$_2$ for all integers $n \geq 3$   How do we prove that $2^n$ divides $t_n$ for all integers $n \geq 1$ by strong induction?  So far, I am having problems with the induction step as I am still trying to grasp the concept of strong induction, but this is what I came up with so far:  Base step:  $t_3 = 32$, which is divisible by 8; and $t_4 = 160$, which is divisible by 16.  $\therefore$ Statement is true when $n=3$ and $n=4$.  Induction step:  Assuming $k=n$ and the statement is true for $3,4,...k$. Prove that $2^k$ divides $t_k$ for $k+1$:  $t_3 = ((2^3 - 2)(2^3) - (2^2)(2^2)) = 2^6 - 2^4 - 2^4 $; dividing this by $2^3$ gives $2^3 - 2^2$ which would be an integer result.  $t_4 = ((2^3 - 2)(2^5) - (2^2)(2^3)) = 2^8 - 2^6 - 2^5 $; dividing this by $2^4$ gives $2^4 - 2^2 - 2$ which would also be an integer result.  $\therefore$ By the logic above, the statement also holds for $k-1$, $k$ as well as $k+1$, thus as required to prove by strong induction.  I believe this is a fundamentally flawed way of trying to prove by strong induction, but this is the only way I can possibly think of. Can someone show a correct method of solving this?


How do I query on a self-defined variable? Example:  SELECT *, MID(dateandtime, 12, 2) as 'xxx' FROM xyz WHERE year = '18-19' AND xxx > 18   Is there a way to use xxx in the query like in the last line of the example?

I need to use an alias in the WHERE clause, but It keeps telling me that its an unknown column. Is there any way to get around this issue? I need to select records that have a rating higher than x. Rating is calculated as the following alias:  sum(reviews.rev_rating)/count(reviews.rev_id) as avg_rating


I am trying to apply a mirror onto my Cheetah model, in edit mode the resting position is how I want the mirror to be applied, however, when it is in object mode, the resting position is that of the animation and the mirror is applied to that position. How can I apply the mirror to the position of edit mode?   How do I fix this?

When I add a mirror modifier it sometimes doesn't mirror correctly, giving me an overlapping mesh. How can I fix this?


$$\lim_{x\to\infty}{\frac{e^x}{x^a}}$$ For $a\in \Bbb R,$ find this limit.  I would say for $a\ge 0$ lim is equal to  $\lim_{x\to\infty}{\frac{e^x}{a!x^0}=\infty}$ (from L'Hopital).  For $a<0$, lim eq. to $\frac{\infty}{0}$so lim doesnt exist.  Is this correct?

In other words, how to prove:  For all real constants $a$ and $b$ such that $a > 1$, $$\lim_{n\to\infty}\frac{n^b}{a^n} = 0$$  I know the definition of limit but I feel that it's not enough to prove this theorem.


Okay, so Maz talks about how that’s Luke’s lightsaber and his father’s, before him. And also explains why Kylo Ren wanted it so badly.  But how’s that even possible...?   In The Empire Strikes Back, Luke loses his arm and the lightsaber when he’s fighting with Darth Vader in Cloud City. That’s the lightsaber Obi-Wan had given Luke in Star Wars: A New Hope, telling him it was his father’s. In Return of the Jedi, when Luke hands himself over to the stormtroopers, one of them gives Luke’s saber to Darth Vader (saying it’s the only thing/weapon he had on him). Anyway, during that conversation, Vader points out “I see you have constructed a new lightsaber.”   Also, it was green (not blue) if I recall correctly, but I’ll let that slide for now.  Later, when Darth Vader loses his arm, he also loses his lightsaber.   (Arms, Lightsabers and Giant Vents do not, a good combination, make.)    So the lightsaber Maz talks about could be Luke’s. But it definitely wasn’t Darth Vader’s or Anakin’s.  Have I missed something or was one of the chopped-arm-lightsabers not lost down a vent?

In The Force Awakens:      Maz Kanata tells Rey that the lightsaber she just picked up and had visions from belonged to Anakin and Luke and now it's hers.   The lightsaber that Luke got from Obi-Wan Kenobi in A New Hope was lost/destroyed when Luke fought Darth Vader in Star Wars: The Empire Strikes Back.  In Return of the Jedi Darth Vader compliments Luke on building a new lightsaber and tells Luke that his skills are now complete.   How could that possibly be the lightsaber that Anakin used originally, and that was then passed on to Luke, when that lightsaber no longer exists?  Writers notes, director's notes, interviews, cast interviews, etc. are welcome. Thanks.


I'm trying to make a game where you control a character via touch on Android devices.  The player will have two degrees of movement.   When you touch the touch screen and move your finger, the game object should move to your finger's location and follow your finger as you move it.  Here is an example of what I'm trying to do:  (@ 1:02).  I already know I need to use Input.touches.  I've tried using Transform.translate and Vector3.Lerp, neither gave me the results I wanted.   Here is some of the code I've tried using:  #pragma strict  var speed : float = 1;  function Start () {  }  function Update () {     if (Input.touchCount > 0 &&          Input.GetTouch(0).phase == TouchPhase.Moved) {           // Get movement of the finger since last frame         var touchDeltaPosition:Vector2 = Input.GetTouch(0).deltaPosition;          var touchPosition:Vector3;          touchPosition.Set(touchDeltaPosition.x,                             transform.position.y,                             touchDeltaPosition.y);           // Move object across XY plane         transform.position = Vector3.Lerp(transform.position,                                                 touchPosition,                                                  Time.deltaTime*speed);     }  }

I am trying to create a 3d game in unity. I have a cube in unity and I want it to move left or right on swipe . It should move to a distance till where user swipe or take their finger off of a screen. I want it to move fast or the cube should move fast on swipe and cube should flow smooth. Like in the gif there is a circle and the user use their finger to move the circle till wherever the user swipe it and it should be instant and I want my cube to move like that at a distance till where user swipe their finger and it should be instant and fast.  I don't know how to do it. Any help is appreciated!


I have text lines like this  blahblah"word1"blahblah"word2"blahblah"word3"   I only want the text between the quotes and without the quotes.  I could do an awk and us the " as a separator.  And then get every second match.  However, is there any way I can just use awk (or another command) to return words between sets of quotes?  so I'd get back word1, word2, word3?  Thanks,

How can I get the value between quotes with an RegEx  for example I want to find all the parameters from the function test  <html>    test("bla");    print("foo");    test("moo"); </html>   The result must be { "bla", "moo" }


I have a shapefile. The coordinates (Lat/Long) are projected as decimal degrees. But, I want to re-project it to meters.   How can I do it with ArcMap?

I put 4 different layers into my ArcMap document, but only one of them will show up on the map! I should be seeing the other 3 layers as well. When I do a Zoom to layer, I can see one layer, but I cannot figure out how to make the other 3 show up at once on top of each other.  Before I opened ArcMap, I used ArcCatalog where I right-clicked 3/4 of the shapefiles and  clicked Properties → Coordinate system → Import and then clicked on my Trees layer, which has the coordinate system I want the other 3 to have. But when I opened ArcMap the 4 layers did not overlap, nor could I move them above or below each other.


A = 0 B = 1  A, B = B, A + B    running 5 times:  the values of B in Python will be 1, 1, 2, 3, 5. the values of B in C will be 1, 1, 1, 1, 1.  Would anyone explain this to me?  #include <stdio.h>  #define TRUE (1 == 1); #define FALSE (1 == 0);  int fibonacci(int sequencia);  int main() {     fibonacci(5);     return FALSE; }  int fibonacci(int sequencia) {     static int antigo = 0;     static int novo = 1;     static int copia = 0;      if (sequencia == 0) {         return TRUE;     }      else {         printf("%i\n", novo);     }     antigo, novo = novo, antigo + novo;     fibonacci(sequencia - 1); }   antigo = 0 novo = 1  def fibonacci(sequencia):     global antigo, novo     if sequencia != 0:         print novo      else:         return True      antigo, novo = novo, antigo + novo     fibonacci(sequencia - 1)  if __name__ == "__main__":     fibonacci(5)

Is there any way of doing parallel assignment in C++? Currently, the below compiles (with warnings)  #include <iostream>   int main() {    int a = 4;   int b = 5;   a, b = b, a;   std::cout << "a: " << a << endl             << "b: " << b << endl;    return 0; }   and prints:  a: 4 b: 5   What I'd like it to print ... if it weren't obvious, is:  a: 5 b: 4   As in, say, ruby, or python.


I want to know how I can make a simple renderfarm. I won't use the network render plugin because it is boring and doesn't support single image rendering (it does so only rendering it on one node). So is there any scalable solution for building a big rendering cluster like ILM (Industrial Light and Magic) is using with loads of cores and ram. As operating system, ubuntu or some other linux distributions should be used.  It should be a free and easy solution.

I have quite a few computers at my disposal- about 100 mac pro's bought 2 years ago, just as many windows PC's of varying age (1-3 years), 50 linux machines and a good few terabytes of storage on a central server. I'm seriously considering getting everything together into a cycles render farm. How can I set something up easily and quickly which will make use of everything I've got?


I installed the AMP in LAMP (already on Ubuntu) for wordpress -- and upon the initial installation & completion I got the wordpress login page, logged in, saw the control panel & stuff; logged out & haven't been able to get back ever since.   When I go to localhost, I get an index page (instead of a login page). Within the /var/www directory, I have an /html dir. & within that is my /wordpress directory. I've fiddled with the 000-default.conf file in my /etc/apache2 directory & have changed the document root back & forth some – currently it’s looking at /var/www – which is giving me html as the parent directory on my localhost page (the wordpress folder is showing up under the parent & I can click to it; just leads to a blank page). I don't have a server alias (which I've seen in a couple different threads).  I know this is going to be a stupid question: but how do I get back to the login page so that I can create a site? I'd like to have a couple different sites & have seen a couple methods for doing that, but it seems like I should figure out this first.   I did the original setup on 17.04 & like 2 days later was the 17.10 upgrade. I don't know if that is important but there seem to be some issues with the upgrade over all & I've been having some issues myself.

I am trying to install Wordpress on Lubuntu. I followed the instructions . Including PHP Apache and MySQL setups. Apache and MySQL appear to be running fine.  However, when I go to http://localhost/blog/, I get the following error:     Neither /etc/wordpress/config-localhost.php nor /etc/wordpress/config-localhost.php could be found.   Ensure one of them exists, is readable by the webserver and contains the right password/username.


I have an online marketplace platform. Because of adding new products/services, I had to update my links to match the new list. Earlier, Google has indexed most of my pages. Now with the new links architecture, most of the results shown by Google are 404. I submitted new sitemap and the new links are yet to be indexed.  Question: Will 404 pages hinder my websites PageRank? If yes, how to mitigate it? Also, how can I get the new web pages indexed fast?  Please let me know your inputs, as most of my traffic is from Google search, fixing this is very important for us.  Thanks, Anji

I am a member of a writing website called HubPages. We are each given a subdomain on which to write articles and are also given access to Google Webmaster Tools for our subdomain.  Upon checking out my stats in Webmaster Tools, I see that Google is running into some 404 errors for two reasons:   I took down an article Google (or someone) got the url totally wrong.   I am essentially getting view-only access for webmaster tools (HubPages must have set it up to allow view only so that a user doesn't mess things up) so I can't submit a url removal request to Google.  Could this be hurting the SEO for my subdomain? If not, are there other problems that could occur for me or for HubPages by leaving these URLs as is and not submitting a removal request? Should HubPages be submitting url removal requests to Google for dead or incorrect urls?


The reputation on the post's revisions page doesn't not have a thousand ("k") or million ("m").    Usually on the post or Users page, the user's reputation with the "k" or "m". Adding the "k" or "m" with the reputation will improve the readability.    Can this be applied to the revisions page too.

The user card in the revision list, for example , shows the exact amount of reputation:  This is not consistent with how the flair works on (all?) other places in the site, e.g. under a post. There, the amount is displayed in units of thousands (k):  (or, in , millions (m).) It used to be consistent, see e.g. :


My US visa  b1/b2 got rejected for the second time under 214 (b). I hold Indian passport, living in KSA for 3 years as resident (Doctor). Since i want to attend a conference in US which will be held in every year in any one of the states , i decided to attended interview in KSA and was rejected. can you please suggest what could be the possibilities  and how i can improve my chances  for next time? how long I should wait before applying for a next chance?   Both interview, I was prepared with invitation letter from organizers of conference, salary certificate from employer, evidence of family ties in KSA, asset documents. Unfortunately consul officer not asked for any of documents and he clearly told that he need only the passport when I tried to give all the documents.  First interview was:   me- good morning officer: good morning me: when i was trying to submit passport and other documents  officer : give only your passport officer: first time to us? me : yes officer : why you are going to us ? me : to attend conference  officer : who sponsoring? me : myself officer: what your job in ksa, how long, salary? me; bla..bla..bla  officer : are you traveling alone ? me : yes officer:are you married?  me : yes, staying here with family  in KSA, have 2 kids. officer:have you traveled to any other country during last 5 years? me : UAE once officer: relative in us ? me : no officer: any relative in canada ? me: no officer: show your bank statement? me : shown officer: cannot issue a visa under 214(b).   Since conference is hardly 2 weeks away, Second attempt was done exactly a week later after submitting a new application. This time I included more documents to prove more ties such as family photo with date,  my first kid's school fee receipts, bonafide  certificate from school , second child's vaccination card, my car documents etc..and all documents organized well. on the day of second interview :  me : good morning ( same officer interviewed for the first time ) officer: good morning me : i was trying to give all documents including passport on top in a transparent file. officer: give only the passport officer: travelling first  time to us ? me : yes officer: purpose?  me ; to attend conference officer:you have been here before? smiling me : yes, last week officer : give your token number, you have to wait  wait until Some one calls you. after a minute i was called for interview by  another officer. officer 2 : hi good morning me : good morning officer 2 : what you doing here me : im working as bla bla  officer 2 : how long in KSA  me:3 YEARS officer 2 : WHERE YOU GOING TO US ? ME :  bla bla to attent conference officer 2 : your salary me : bla bla officer 2 : travelling alone me : yes officer 2 : dates of your conference? me : bla bla officer 2 : have you traveled TO ANY COUNTRY DURING PAST 5 YEARS ? ME : UAE  officer 2 : with in  past 3 years have you traveled to any country other than India ? me : no officer 2 :  sorry, your visa got denied under section 214(b).   Both officers not asked for any other documents/ ties  and so i didn't gt  a chance to show/ explain the ties.  what could be the possible reason for rejection? how can i improve my chance if iam applying for nex time either for conference / for sight seing with my family ?

I went for B1 U.S. Visa at the U.S. Embassy in Delhi.   Interviewer: *Good Morning*. Me: *Good Morning* Interviewer: *What is your designation?* Me: *I am a Software Engineer.* Interviewer: *What is the name of your company?* Me: *It is XXX (I replied).* Interviewer: *What is the name of your client?* Me: *It is YYY (I replied).* Interviewer: *Have you ever been to U.S. before?* Me: *NO* Interviewer: *Have you ever been abroad before?* Me: *NO*   At this point he rejected my Visa with letter mentioning 214 (b) as the reason. I don't know why he actually rejected it.  But, I have decent 2+ years of experience with my company. And, I was going on a business meeting with the client. I would have come back after 2 weeks.  I don't know if re applying will help.


In French language, I will say "Comment ne pas être repéré". But I want to translate it into English. Do we say "How to not be spotted" or "How not to be spotted"?

This is one thing that keeps bugging me, and maybe there's a direct answer. Grammatically, which one is more correct of these two?  Does it make a difference?  I tried not to do that. I tried to not do that.


I'm seeking a book I read as a kid in the 80s about two orphans who were (I think) in the foster system. Brother and sister. He always told her tales of a magical land with a name that I think began with Nangri-something or similar. One day there waas a fire and they died, possibly him before her. Awakening, they were in that kingdom of Nangriwhatsit.  They went on to have heroic adventures before dying again and as they lay dying, he began telling her stories of the next kingdom they would arrive in...

This is a tough one, it has eluded me for years!  It is a TV show which opens with two brothers, maybe in 17th or 18th century London. One is around 16, the other is 11 or so and he idolises his older brother. There is a fire, the older brother died but seems to return or summon the younger one to a magical land called something like "yanki-hola". They were transported to a village in, I think, medieval times. I think there were some adventures there against a local bad baron or duke.  I really just remember that it was sad and unsettling when the older brother died. Has anyone ever seen anything similar to this? I have tried for years to find an answer.


I previously asked  about why my transparent fades weren't showing up or printing and it seems that the transparency feature in pdfs isn't uniformly supported.  So my new question is this: is there a way to draw something that gives the same visual effect as transparency without using that feature?  I'll use the same MWE:  \documentclass{standalone} \usepackage{tikz} \usetikzlibrary{fadings}  \begin{document} \begin{tikzpicture}  \fill [blue!80!black, path fading=east] (0,0) --++ (90:0.3) --++ (0:6) --++ (-90:0.3) -- cycle;  \end{tikzpicture} \end{document}

I have a problem using opacity in TikZ. Whenever I use it somewhere in a picture, I get weird side-effects: colors in (some) other parts of the documents are changed apparently randomly and it makes the text look semi-bold and somewhat blurry.  I only see this effect in Acrobat. Other pdf viewers I tried display the document correctly.


I am using a 2 column document and have a 2 column figure placed at the top of the page. The problem is that the figure is showing up on page 3 instead of page 2. It is the first figure in my document.  \begin{figure*}[t!]\         \centering         \includegraphics[width=\textwidth]{results}\\         \caption{Recall vs. IOU for class \textit{car} with an average of 500 proposals. Best viewed in colour.}         \label{fig:results}     \end{figure*}

How to influence the position of float environments like figure and table in LaTeX?   This is a general question and should collect useful answers for all users. I hope we can use this as a reference


Let $(\mathbb{Q},+)$ be additive group of rational numbers. If $G_1, G_2$ are two nonzero subgroup of $(\mathbb{Q},+)$, prove that $G_1\cap G_2\neq\{0\}$.  My approach :  Take $p/q\in G_1$ and $a/b \in G_2$. Then $p/q+p/q+..=p \in G_1 $ ($q$ times addition). Similarly $a\in G_2$. Now we can always choose $p$ and $a$ as positive because in group their inverse are of opposite parity.   Now set $l=lcm(p,a)$. Since $l=\frac{pa}{d}$ where $d=\gcd(p,a)$ one finds $l\in G_1$.   Reason : Just  $p+...p=l$ where (addition is done $\frac{a}{d}$ times).  similarly $l\in G_2$.  So $l\in G_1\cap G_2 $. Hence $G_1\cap G_2\neq \{0\}$. Proved   I would like to know if my solution is correct. This was supposed to be a tough problem. So it feels like i have committed some mistake in proof. Thank you.

I need to prove that any two nontrivial subgroups of $\mathbb{Q}$ have a nontrivial intersection as part of a larger proof that $\mathbb{Q}$ cannot be represented as a nontrivial direct product.    (Yes, I realize that there are other ways to prove that $\mathbb{Q}$ cannot be represented as a nontrivial direct product, but I am not interested in those, and will not accept answers showing me how to do that).  Based on the density of the rationals, I guess this idea kind of makes sense, but I am doing this proof for an abstract algebra class, and I don't think real analysis proofs would be accepted.   Everywhere I've looked online has said this is "trivial" or "easy to see" without bothering to actually prove it for those of us mere mortals who don't see it as such. As for myself, I have literally no idea where to even get started proving this. Could somebody help me figure this out (without giving me cutesy examples that aren't really all that related with the expectation that I should be able to figure it out from looking at those - that's not really how my brain works)?  Thank you.


Well, the title question is straight-forward. Elemental Affinity states     Starting at 6th level, when you cast a spell that deals damage of the type associated with your draconic ancestry, add your Charisma modifier to that damage.   For example, Wand of Fireballs states     While holding it, you can use an action to expend 1 or more of its charges to cast the Fireball spell (save DC 15) from it.   Note that Elemental Affinity does not require the Cast a Spell action, however, it requires that you are the one casting the spell. Does it count if it comes from the magic item? I feel that this should be an easy answer but I'm a little confused here.

This question is updated to request additional answers and details in light of information now available in the Dungeon Master's Guide. In the released DM basic rules, Lost Mine of Phandelver, Hoard of the Dragon Queen, and the DMG teaser there are wands, staves, and rings that you can use to cast spells.  Do abilities that trigger from casting a spell activate when casting a spell from an item?  Can the character modify the spell using class abilities when casting a spell from an item?   Examples include:  An abjurer Wizard's arcane ward recovering hit points from a Dispel Magic cast from a Ring of Spell Storing  A sorcerer using Twinned Spell on a ray of enfeeblement from a Staff of Power  An evocation wizard using Sculpt Spell on a fireball from a Wand of Fireballs.   Now that the DMG is out we have some clearer rules on casting spells from items (DMG p. 141):  Some magic items allow you to cast a spell from the item.  The spell is cast at the lowest possible spell level, doesn't expend any spell slots, and requires no components, unless the item's description says otherwise  The spell uses its normal casting time, range and duration, and the user of the item must concentrate if the spell requires concentration. A magic item, such as certain staffs, may require you to use your own spellcasting ability when you cast a spell from the item.  Does whether or not you can apply class abilities to the casting of the spell depend whether the item uses the user's own spellcasting ability (such as the Staff of Fire) versus an item that comes with a fixed spellcasting ability built-in (such as the Wand of Fireballs)? Does it matter if it's something that triggers more or less automatically like Arcane Ward, versus something you have to control, like Careful Spell?


I'm not sure how to phrase this question correctly, but the gist is that, an external party will access our Salesforce environment via REST Api and retrieve more than 50,000 account records. Now I know we can only query 50,000 records via SOQL and that we need to do pagination to get more. However, we're not developing a UI, we just want to retrieve account records in the Salesforce environment and we expect the return would be more than 50,000 records. Any help would be much appreciated. Thanks.

I was using simple-salesforce library to query the salesforce through REST API but getting query timeout error. I have not added the LIMIT keyword in the query as I thought salesforce will automatically only return 2000 result and after that, it will provide nextRecordURL for other 2000 records.  My Current implementation looks like this,  json_response = self.sf_api_instance.query_all_custom(query) parent_mapper = SalesForceMapper(json_response, field_mapping=field_mapping)  self.send_data(parent_mapper, object_type) is_done = json_response.pop("done", False) next_records_url = json_response.pop("nextRecordsUrl", '') while True:    if not is_done:       json_response = self.sf_api_instance.query_more(next_records_url, True)        parent_mapper = SalesForceMapper(json_response, field_mapping=field_mapping)        self.send_data(parent_mapper, object_type)       is_done = json_response.pop("done", False)       next_records_url = json_response.pop("nextRecordsUrl", '')    else:       break   So is my understanding is right or I need to provide LIMIT in every query.


I think here is a very strange python code, but i don't know the reason：  In [7]: a = [[]] * 3  In [8]: b = [[], [], []]  In [9]: a == b Out[9]: True  In [10]: a[0].append(1)  In [11]: b[0].append(1)  In [12]: a == b Out[12]: False  In [13]: a Out[13]: [[1], [1], [1]]  In [14]: b Out[14]: [[1], [], []]   Why a is [[1], [1], [1]] after a[0].append(1)?   A similar problem is：  In [15]: c = dict.fromkeys(range(3),[])  In [16]: d = {0:[], 1:[], 2:[]}  In [17]: c == d Out[17]: True  In [18]: c[0].append(1)  In [19]: d[0].append(1)  In [20]: c == d Out[20]: False  In [21]: c Out[21]: {0: [1], 1: [1], 2: [1]}  In [22]: d Out[22]: {0: [1], 1: [], 2: []}   In my understand, a is b, and c is also equal to d, but it isn't. WHY? can anyone help me? Thanks very much!

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


Here are a group of mathematical expressions:  $$arg\ \underset{\theta}{max} \underset{n}{\prod}P(Y_n|\theta)$$ $$=arg\ \underset{\theta}{max} \underset{n}{\prod}\theta^{Y_n}(1-\theta)^{1-Y_n}$$ $$=arg\ \underset{\theta}{max} \sum log\theta^{Y_n}(1-\theta)^{1-Y_n}$$ $$=arg\ \underset{\theta}{max} \sum[Y_n log\theta + (1-Y_n)log(1-\theta)] $$ Optimizing problem: $$=-arg\ \underset{\theta}{min} \sum[Y_n log\theta + (1-Y_n)log(1-\theta)] $$   I am trying to align them to the left. I tried putting them inside %\begin{align*} ... % \end{align*} without $$ signs. But no luck.

I wanted to left align a set of equations. I've tried the solution provided in  . It worked. But, I wanted to have a single equation number for the entire flalign in order to refer to it later. Like in case of equation+split. While using equation+align, I am able to get it. But, if I use equation+flalign the equations are still being centered. Is there a way to do it?  Example using equation+align,  \begin{equation}      \begin{align}       \mbox{Minimize } & x_1+x_2+x_3 \\       \mbox{Subject to} & \\        & x_1+x_2 \leq 10 \\        & x_2+x_3 \leq 8 \\        & x_1+x_3 \leq 5       \end{align} \end{equation}   I would like to do this while the equations are left aligned.  It will be even better if the equations can be spaced a little (for example, 1 cm) from the left margin instead  of starting from the left margin.  Thanks in advance


I am creating a logfile from kermit named the current date (which is in the format of DD MMM YYYY - which can not be changed AFAIK), and using the file name as today's date.  I then have a Bash script to read the file and I want to tail -n1 the file.  if I do      filename=$(date +%d\ %b\ %Y) && echo $filename   I get      23 Feb 2015   which is what I want and expect. However if I then do      filename=$(date +%d\ %b\ %Y) && tail -n1 $filename   I get      tail: cannot open `23' for reading: No such file or directory     tail: cannot open `Feb' for reading: No such file or directory     tail: cannot open `2015' for reading: No such file or directory   I am not sure what is causing this, probably down to the the way I have string formatted I guess since I get the same if I use tail or cat?

Or, an introductory guide to robust filename handling and other string passing in shell scripts.  I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some file names).  I encountered a problem such as the following:   I have a file name containing a space hello world, and it was treated as two separate files hello and world. I have an input line with two consecutive spaces and they shrank to one in the input. Leading and trailing whitespace disappears from input lines. Sometimes, when the input contains one of the characters \[*?, they are replaced by some text which is is actually the name of files. There is an apostrophe ' (or a double quote ") in the input and things got weird after that point. There is a backslash in the input (or: I am using Cygwin and some of my file names have Windows-style \ separators).   What is going on and how do I fix it?