Imagine a "rope" (for want of a better word) is wrapped all the way around the Earth, to the point that you can hold both ends.  There is no slack on the rope, i.e. it doesn't stretch. It also isn't caught on anything on the Earth's surface and no friction applies to it, if that matters.  If I pull one end in one hand, would the other end move instantaneously? I don't see why it wouldn't but it's hard to imagine it moving straight away when it's wrapped around such a distance.  I'm no physicist so I might not be accounting for something obvious, or it is just that simple. Because of this I also wasn't sure how to tag this. Thanks.

Is it possible for information (like 1 and 0s) to be transmitted faster than light?   For instance, take a rigid pole of several AU in length. Now say you have a person on each end, and one of them starts pulling and pushing on his/her end.   The person on the opposite end should receive the pushes and pulls instantaneously as no particle is making the full journey.  Would this actually work?


I want to disable clickjack protection. I have tried to log a case in salesforce support to turn it off (by default it is enabled and we can't change it).  Is there any way to log a case to turn-off this feature of salesforce?

i want to enable the iframe on visualforce pages.i am going to disable it from      Administration Setup" -> "Security Controls" -> "Session Settings   but it is disabled. how can i disable/uncheck it.   Update:   i want to uncheck:  clickjack protection for non-setup Salesforce pages  and    clickjack protection for non-setup customer Visualforce pages with headers


How do i engrave or put desired seams or thin crevices in objects?. I've included a pic for an example. Is there possibly an addon i could get to make such things easier or more intuitive?. Types of engraving i'm shooting for. straight lines, curved or crescent lines and abstract shapes/designs.

I'm want to create the hidden blade from assassin's creed brotherhood (video game)  I created the model and stuck on how to create engravings on the hand guard of hidden blade  Here are some reference pictures    The engravings on the blade doesn't has that much of a bump to them, so I'm going to add them in textures  But ones on the hand guard does   So my question what options do I have to make them?  I want it to be details just like in the first picture  So I don't think a texture with a bump map will do   PS: Still a noob in blender so... sorry if this question is stupid


Is it possible to use a 2009 imac as a display for a 2017 macbook pro? If so, what cable would I need to make this work? Ideally with a mini display port to usb-c cable it would just work but I have my doubts.

I wanted to use a mini display-port cable then use "target display mode" to make the iMac an external display, but I just read that early 2009 iMac's don't have target display mode as a feature.  Anybody knows of a solution?


How to find the following partial derivative   \begin{align} \frac{\partial}{\partial x_i} ( {\bf x}-{\bf c})^T A  ( {\bf x}-{\bf c}), \end{align}   where ${\bf x}$ is a vector of length $n$ and  $A$ is a strictly positive definite matrix, and  ${\bf c}$ is just a fixed vector.   My plan was to re-write it in terms of a double sum and take the derivative.

It's stated that the gradient of:  $$\frac{1}{2}x^TAx - b^Tx +c$$  is   $$\frac{1}{2}A^Tx + \frac{1}{2}Ax - b$$  How do you grind out this equation? Or specifically, how do you get from $x^TAx$ to $A^Tx + Ax$?


Let's say I want to write Definition 1.1 of a source I call \cite{fr82}. I can write \cite[Definition 1.1]{fr82} without any trouble, and I can write \begin{defn}[\cite{fr82}] blah blah \end{defn}  without any trouble. However, when I write \begin{defn}[\cite[Definition 1.1]{fr82}] blah blah blah blah \end{defn}  I get the following error: Runaway argument? Definition 1.1) ! Paragraph ended before \@citex was complete. <to be read again>                     \par  l.488 \begin{defn}[\cite[Definition 1.1]                                         {fr82}]\label{defn:geom_fib} I suspect you've forgotten a `}', causing me to apply this control sequence to too much text. How can we recover? My plan is to forget the whole thing and hope for the best  Any idea for how to fix this?

How do I create something like this without getting any errors?  \begin{thm}[\cite[page 10]{ABC2011}] ... \end{thm}   I tried putting various things into {...} brackets, but not eliminating any errors. I probably have misunderstood something about how LaTeX works in the background and the AMS packet:  \usepackage[amsmath,thmmarks]{ntheorem}


I’ve found sites that say it’s ok to start a brine for a partially frozen turkey. My question is, when you thaw a turkey using the cold water method, they say to change the water every 30 minutes. If you’re brining a partially frozen turkey, do you have to change the brine (including all the herbs and whatnot) every 30 minutes as well?

What are the proper ways to thaw foods?   Are there any advantages or disadvantages to them?


I have just installed Ubuntu 17.10 and my ASUS wireless adapter is not found.  The result of lspci -v:  Network controller: Broadcom Limited BCM4360 802.11ac Wireless Network Adapter (rev 03) Kernel driver in use: bcma-pci-bridge Kernel modules: bcma   I do not have an internet connection on the system. I have never had an issue with this system and the wireless adapter on previous versions of ubuntu (as far back as 16.04). Have the necessary drivers been removed from the linux kernel? How do I get the drivers installed without an internet connection?

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


What is the difference between specialization  and specialisation ? where am i use   specialization   and specialisation  what does meaning of both.?

I have seen words which are spelled either with a "z" or with a "s"  like "optimizer" and " optimiser".  I thought that the ones with "z" are wrong but on searching the web I found that both are correct. Why so? Is there any difference in the use also?


I know 300 is not the cap, so this is not a duplicate question. My flag weight stopped at exactly 300 a few days ago, at the same time I gained the privilege to Cast close and reopen votes, so I'm wondering if that's related, or if this is possibly a bug just affecting my account?  Here is my profile:   When I click on my flagging summary It shows my last flag as being on July 24th. However I've been on everyday since then to get my 200 rep, and I've flagged an average of about 5-10 posts per day too, but none of those flags are showing up in my flagging summary. Most, if not all, the flags I've made have been valid and the posts have been closed. My username has been listed under the post saying it was closed / moved by me and 4 others, so my flags are working. They're just not showing up flagging summary, or affecting my flag weight.  Anybody else ever had this before, or know the cause? Is it a bug?

Possible Duplicate:          I recently got the ability to cast close votes. So, even if I flag a question as 'not constructive' or 'not a real question', it is still considered as a close vote. What is strange is that my 'helpful flag' count has stopped increasing after this change. Or at least it doesn't increase in cases where my flagging was automatically changed to a close vote and the post actually was closed. Is this how it is supposed to be?   I am guessing that once the post gets closed, the moderators are probably not bothered about marking flags as helpful. The only problem is that the Deputy badge will be much more difficult to get now. Earlier all the flags were getting converted to helpful, but now they just go in as close votes and don't show up on my profile page.


Given that Black Library offers an enormous number of books, I was wondering what the process looks like which ensures that all the stories do align nicely and do not contradict each other.  Is there a review board which checks new books? How does e.g. Dan Abnett know what to write and so it does not contradict what Guy Haley writes? Is there a committee which desires how certain stories will develop?

Part of the success of the MCU has been the hand of Kevin Feige overseeing the various projects ensuring continuity.   Do Games Workshop/Black Library have a similar role? It certainly feels in recent years that the books have become more in sync, in particular with characters and events in the Horus Hersey books feeding into the more recent (timeline wise) stories, with characters and events being referenced back and forth.


How is the process when a constructor parameter is a list and list is updated through an external function? There is "pass-by-reference" system when parameter is an array or list. But how is the object updated? Is any copy constructor used or how?  Let's assume that we have two user-defined classes Point and Curve. We filled our list with Point objects. Then we construct our Curve object with List of Points.  List<Point> points=new ArrayList<>(); points.add(Point(0,1)); points.add(Point(0,0)); Curve c=new Curve(points);   Then we add a Point object to our List of Points.  points.add(Point(1,1));   How is Curve object is affected?

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?


working on this code since this morning all day, it a demo from a book online  for some reason getting null pointer exception at main() and also logic seems bit not working, can someone spend bit of his time  gosh cant find the problem there thanks for help people  class Currency {     private int amount;      public Currency(int a) {         this.amount = a;     }      public int getAmount() {         return amount;     } }  interface DispenseChain {     public void setNextChain(DispenseChain nextChain);      public void dispense(Currency cur); }     class Dollar50Dispenser implements DispenseChain {     private DispenseChain chain;      @Override     public void setNextChain(DispenseChain nextChain) {         this.chain = nextChain;     }      @Override     public void dispense(Currency cur) {         if (cur.getAmount() >= 50) {             int num = cur.getAmount() / 50;             int remainder = cur.getAmount() % 50;             System.out.println("Dispensing " + num + " 50$ note");             if (remainder != 0) {                 chain.dispense(new Currency(remainder));             } else {                 chain.dispense(cur);             }         }     } }     class Dollar20Dispenser implements DispenseChain {     private DispenseChain chain;      @Override     public void setNextChain(DispenseChain nextChain) {         this.chain = nextChain;     }      @Override     public void dispense(Currency cur) {         if (cur.getAmount() >= 20) {             int num = cur.getAmount() / 20;             int remainder = cur.getAmount() % 20;             System.out.println("Dispensing " + num + " 20$ note");             if (remainder != 0) {                 chain.dispense(new Currency(remainder));             } else {                 chain.dispense(cur);             }         }     } }     class Dollar10Dispenser implements DispenseChain {     private DispenseChain chain;      @Override     public void setNextChain(DispenseChain nextChain) {         this.chain = nextChain;     }      @Override     public void dispense(Currency cur) {         if (cur.getAmount() >= 10) {             int num = cur.getAmount() / 10;             int remainder = cur.getAmount() % 10;             System.out.println("Dispensing " + num + " 10$ note");             if (remainder != 0) {                 chain.dispense(new Currency(remainder));             } else {                 chain.dispense(cur);             }         }     } }     class DemoChainResponsibilityPattern1 {     private DispenseChain c1;     public DemoChainResponsibilityPattern1() {         c1 = new Dollar50Dispenser();         DispenseChain c2 = new Dollar20Dispenser();         DispenseChain c3 = new Dollar10Dispenser();         // set the the chain of responsibility         c1.setNextChain(c2);         c2.setNextChain(c3);     }      public static void main(String[] args) {         DemoChainResponsibilityPattern1 dispenser = new DemoChainResponsibilityPattern1();         while (true) {             int amount = 0;             System.out.println("Enter amount to dispense: ");             Scanner input = new Scanner(System.in);             amount = input.nextInt();             if (amount % 10 != 0) {                 System.out.println("amount must be in multiple of 10s");                 return;             }             // process the request             dispenser.c1.dispense(new Currency(amount));         }     } }

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


I am trying to find out if there is anyway to create a windows user account that has time restrictions set to it.  The problem I am having is I have multiple users that need to use this one computer but I want to restrict their use to only one hour.  What I would like to do is the log the person into the user account and after an hour the computer would automatically log the windows user out of the computer.

I have 4 kids so the battle for time on the living room computer never ceases, I am also implementing an attempt at some level of control over how much time the kids get based on their behavior etc during the week. Ideally I would like to be able to set each profile up to have only a certain allotment of time, say 2 hours that they can use and once that two hours is nearly up it warns them and once complete it automatically logs them out.  I know the family control stuff can limit the time frames during which they can login but it does not seem to allow this quantity based control I am looking for...  Any other options in the market that you know of?


I am running a pooled OLS regression for my thesis. My adjusted r square is 0.74 which is quite high compared to other published studies. I have checked for normality of residuals, serial correlation and homoscedasticity. All the 3 tests meet the conditions for OLS. Should I be concerned about the high adjusted r square? Is there any test I could do to know whether the regression model has no other flaws?

I've fitted my model and am trying to understand whether it's any good. I've calculated the recommended metrics to assess it ($R^2$/ AUC / accuracy / prediction error / etc) but do not know how to interpret them. In short, how do I tell if my model is any good based on the metric? Is an $R^2$ of 0.6 (for example) sufficient to let me proceed to draw inferences or base scientific/business decisions?     This question is intentionally broad, to cover a wide variety of situations that members frequently encounter; such questions could be closed as duplicates of this one. Edits to broaden the scope beyond the metrics mentioned here are welcome, as are additional answers - particularly those that offer insight about other classes of metrics.


I remember starting, and losing, a book in the late 80s, early 90s, that I have been trying to  remember for a while now.  It's not much to go on, I realise, but the main crux of the plot, until I left the book in a phone booth :/, was an ice age (either implied or stated, I can't recall) was starting, and a (I think implied) glacier was moving closer to the main castle or walled city of the novel.   The setting was not specifically High Fantasy, but a medieval style setting.  The interesting thing I always remember about the book was that the antagonist appeared to be the ice itself, slowly, but inexorably, getting closer.

I read a trilogy of books 5-10 years ago (it could have been an old story by then though) and went to recommend to a friend - but I can't for the life of my remember the author/titles.  In this world, magic and blacksmithing are linked somehow - "mastersmiths"enchant their creations while making them. There are few true "mastersmiths" who can craft in this way, and are held in high, almost god-like esteem.  What I remember:  The main protagonist is recruited by a mastersmith who teaches him the trade     it turns out this master is a bad guy, and he was helping him build some mega-sword of super-death   Later in the story he goes into a sort of self-imposed exile, not making anything too fancy     until someone talks him out of it? I think?   I'm hazy on the main plot details in this one, but     near the end of the book, he forges what to modern eyes would be an iron-man suit, possibly fighting a dragon...   Can anyone help?


Let $Z$ be an exponential random variable and $R$ an independent nonnegative random variable. Show that $$ P(Z-R > u | Z > R ) = P(Z > u) $$ From here, I can use Bayes Theorem to split the Left Hand Side, and I know that I have to integrate them.  However, I'm not sure how to exactly to proceed from here. I know that $u \geq 0$.  Any help would be greatly appreciated.  Thanks!

It is true that $P(X>t+s|X>t)=P(X>s)$ for certain values $t$ and $s$.  However, how can I show that this still holds if:   $T$ is a continuous random variable. That is $P(X>T+s|X>T)=P(X>s)$ Both $T$ and $S$ are continuous RVs: $P(X>T+S|X>T)=P(X>S)$   All the random variables are independent.


I was reading up on some C# and came across this snippet of code from:   The code was:  private int _name;  public int Name {     get { return _name; }     set { _name = value; } }   Can you please explain what is going on in this code snippet here?  Thanks!

In C#, what makes a field different from a property, and when should a field be used instead of a property?


I want to download windows 10 on by Ubuntu 16.04 to dual boot. There are so many ways to download Ubuntu after Windows, but I have no idea of downloading Windows After Ubuntu. Can anyone help?

I have Ubuntu on my laptop. Now I want install Windows 7 in a dual-boot. How can I do this? I can't lose my Ubuntu files, and I'm afraid that I might break . Go  for UEFI only!


Prove that $\displaystyle 1 < \cos A+\cos B+\cos C \leq \frac{3}{2}$ where $A+B+C = \pi$  Attempt: $\cos A+\cos B+\cos C= 1+4\cos A\cdot \cos B\cdot \cos C$  Now $\displaystyle \cos A\cdot \cos B\cdot \cos C=\frac{1}{2}\cos A\left[\cos (B-C)-\cos A\right]\leq \frac{1}{2}\cos A(1-\cos A)\leq \frac{1}{2}\left[\frac{\cos A+1-\cos A}{2}\right]^2 = \frac{1}{8}$  so $\displaystyle \cos A+\cos B+\cos C\leq 1+\frac{1}{2} = \frac{3}{2}$  could some help me how to solve for minimum , thanks

Here is what I did, tell me whether I did correct or not: \begin{align*} y &= \cos A + \cos B + \cos C\\ y &= \cos A + 2\cos\left(\frac{B+C}2\right)\cos\left(\frac {B-C}2\right)\\ y &= \cos A + 2\sin\left(\frac A2\right)\cos\left(\frac {BC}2\right) && \text{since $A+B+C = \pi$} \end{align*}  Now for maximum value of $y$ if we put $\cos\left(\frac {B-C}2\right) = 1$ then \begin{align*} y &\le \cos A + 2\sin\left(\frac A2\right)\\ y &\le 1-2\sin^2\left(\frac A2\right) + 2\sin\left(\frac A2\right) \end{align*}  By completing the square we get  $$y \le \frac 32 - 2\left(\sin\frac A2 - \frac 12\right)^2$$  $y_{\max} = \frac 32$ at $\sin\frac A2 = \frac 12$ and $y_{\min} > 1$ at $\sin \frac A2>0$ because it is a ratio of two sides of a triangle.  Is this solution correct? If there is a better solution then please post it here. Help!


I have 128GB SuperSonic Rage 2    and my pc shows only 117GB:    I tried to format with BOOTICE  and then . Still shows 117 GB.   Somewhere I read that USB calculate capacity 1GB = 1000MB and computer 1GB = 1024MB. If this is true, my capacity 117GB is wrong anyway because 128000MB / 1024 = 125GB  Please help me give me back full size. Thank you!

The du command shows 43G in use. I'm not sure whether that's base 2 in the sense of 2^30 or if it's base 10, in the sense of 10^9.  But anyhow -   Running this du command from cygwin, to see the size of the windows directory (done from an administrative command prompt - since it seemed to have some issues reading some directories otherwise)  user@comp ~ $ du -sh /cygdrive/c/windows 43G     /cygdrive/c/windows   Windows Explorer  which I understand shows it in 'base 2', (a larger unit for KB,MB,GB than base 10 KiB, MiB e.t.c.), and hence a lower quantity of that larger unit is required to give the same result.    Windows explorer shows      46.6GB  , over 50 billion bytes.    (according to windows explorer)  or  46.8GB  , over 50 billion bytes. (according to windows explorer)  So, du aside.  Even if I multiply the larger figure, 46.8GB  by 1.048576 then I get 49.0733568 that's not over 50 billion. So that's part A of the question,  but then also, part B of the question, why is the du figure so low.


I just noticed that my flair no longer shows just the pictures and summed reputation from sites that I have 200+ rep. Instead, it's summing the reputation from all of my registered sites (and showing as many site pictures as it can fit), regardless of my total reputation at those sites.  However, the flair page still says:     please note that only sites where you have more than 200 reputation will appear   My flair was not doing this as of earlier this week.  Is this a bug or did the policy/mechanics of how flair works change?

I took a look at my profile, where I stuck my flair. Here's the flair:    However, I don't have 28k rep. According to chat, I have 19.7k.  Note: I know about the combined flair - I've had this in my profile for at least a year. It had been showing me the same as in chat, now it isn't.   What is going on here?  Edit: I'm reporting a bug here, that the combined flair is not showing the correct number, as it has in the past.


Inspecting the stdout the invocation of  utility without supplying an operand it returned a name=value pair whose meaning I don't understand nor was able to find any documentation   $ env ... !::=::\ ... TERM=cygwin MSYSTEM_PREFIX=/mingw64 ...   In the POSIX specification it is stated that   STDOUT     If no utility operand is specified, each name= value pair in the     resulting environment shall be written in the form:      "%s=%s\n", <name>, <value>    I'm using msysgit on a machine running Windows 10.  $ git --version git version 2.22.0.windows.1  $ printf "%s\n" $BASH_VERSION 4.4.23(1)-release   Started a new session and the result is the same.  Executing the same env command on cmd.exe returns   C:\>env !::=::\ !C:=C:\ ...   What is the meaning and purpose of this name=value pair?

Using Cygwin, I installed Environment Modules by downloading source code, running configure, make, and make install. Every time I run a module command, I get:  init.c(718):WARN:165: Cannot set TCL variable '!::'   I've traced this down to the fact that Cygwin has the following environment variable set:  $ env | grep :: !::=::\   Does anyone know what this is, where it is set, why it might be necessary, or how to get rid of it?  I might add that it's exceedingly difficult to Google, or even get to display correctly in Markdown.    From the comments:  $ unset '!::'  -bash: unset: `!::': not a valid identifier


$echo red | grep -q red $echo $? 0   'grep -q' turns off writing to standard output. The $? exit status is 0 if a match is found, otherwise not 0. This is pretty much the explanation for the code above. I want to know more about "$?". What is it??

The question is pretty straight forward. I can get the exit code of the previous command by using $?. But what exactly is it?  I don't think it is a variable, because you can't have any special characters in the name of variable other than _.  foo?foo=10   will result in the error: foo?foo=10: command not found  So if it is not a variable, what is it? Are there others like it?


Why does the shadow-root styles put display none on my .fa-xxx classes?  The shadow-root thing adds the classes I use to a display none pile, but only the specific ones I add!  I'm using PHP to include navigation, footers and such, but these don't get effected by it. For example it works just fine in my navigation. There it displays the font just fine.  What is causing this, and how do I control it?

(clickable)  Mainad has a valid height and width, however it isn't shown like subad1/subad2. Which are in essence exactly the same! (just a different background image).  Firebug shows my div as greyed out for some weird reason. Replacing the contents of mainad with just some text doesn't solve the problem (problem isn't related to inner elements)..   What's going on?! :(


I have generated a certificate using openssl with the below command.  openssl ecparam -out <output_file> -name secp256r1 -genkey   What would be the RNG used in this case? and is it cryptographically secure?

I'm wondering if the openssl rand command produces cryptographically secure random bytes. For example when in need for a random password or token:  openssl rand -hex 32   The man page unfortunately does neither state it's cryptographically secure, nor that it's not.  On the one hand, I think this is openssl, its sole purpose is to do cryptography. On the other hand, the man page states something about reading and writing seed data instead of directly querying a CSPRNG.  So it is somewhat unclear for the end user. Does someone know?


I've been trying to mount an ISO file on Windows Server 2008 without success. I've tried MagicISO, Daemon Tools, and Pismo Disk Mounter, but all of them give me some error or another. I'm guessing this is some security issue, but I'm not sure how to get around it. Has anyone had luck with this?

I followed the instructions on . I don't see the the drive after mounting.  I used the Virtual CD-ROM Control Panel v2.0.1.1 from microsoft.   Anyone have a simple clean way of mounting ISO image on Win 2008 Server?  I would be mounting on a production box, so, can not reboot. I wanted something simple and easy to use and free. It is for a one time use to install software that was packaged in an ISO image.


I learned that sudo echo hello > root-owned-file.txt does not work because the redirection does not inherit root privilege, so you need something more like echo hello | sudo tee root-owned-file.txt or echo hello | sudo cp /dev/stdin root-owned-file.txt. However, grep can use --color=tty to add color when redirected to a tty, but not to other destinations. Is redirection totally separate from the subject process, and if so, how does grep 'know' when to omit colors?  My intuition is that there is more to redirection than just channels 1/2/3; my current theory is that grep sends both colored and plain output to several variants of channel 1, and the parent shell selects the correct variant to redirect to the destination based on whether or not the destination is associated with a tty. Alternatively, the parent shell might prepare the destination process/file and send a signal or file descriptor of some kind to the source process; however, this would have implications on the sequential nature of the pipeline, which I had assumed was more strict. For example, the next command in the pipeline might set a flag before yielding a file descriptor, and the source command might depend on that flag's original value, causing a race condition if the pipeline sequence is not strict.

I want to know if there's any way to check if my program can output terminal output using colors or not.   Running commands like less and looking at the output from a program that outputs using colors, the output is displayed wrong, like  [ESC[0;32m0.052ESC[0m ESC[1;32m2,816.00 kbESC[0m]  Thanks


I'm trying to learn reinforcement learning and this topic is really confusing to me. I have taken an introduction to statistics, but I just couldn't understand this topic intuitively.

My background is computer science. I am fairly new to monte carlo sampling methods and, although I understand the math, I have hard time coming up with intuitive examples for importance sampling. More precisely, could someone provide examples of:    an original distribution one cannot sample from but one can estimate an importance distribution which can be sampled from and adequate for this original distribution.


I'm trying to understand what is going on when I remove the intercept in my model using y ~ x + 0  Why do these models have the same predicted values despite one not having the intercept?  glm1 <- glm(Survived ~ Pclass + Sex + Age, family = binomial(link = "logit"), data = titanic_train) glm2 <- glm(Survived ~ 0 + Pclass + Sex + Age, family = binomial(link = "logit"), data = titanic_train)  > summary(glm1)  Call: glm(formula = Survived ~ Pclass + Sex + Age, family = binomial(link = "logit"),      data = titanic_train)  Deviance Residuals:      Min       1Q   Median       3Q      Max   -2.7270  -0.6799  -0.3947   0.6483   2.4668    Coefficients:              Estimate Std. Error z value Pr(>|z|)     (Intercept)  5.056006   0.502128  10.069  < 2e-16 *** Pclass      -1.288545   0.139259  -9.253  < 2e-16 *** Sexmale     -2.522131   0.207283 -12.168  < 2e-16 *** Age         -0.036929   0.007628  -4.841 1.29e-06 *** --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  (Dispersion parameter for binomial family taken to be 1)      Null deviance: 964.52  on 713  degrees of freedom Residual deviance: 647.29  on 710  degrees of freedom   (177 observations deleted due to missingness) AIC: 655.29  Number of Fisher Scoring iterations: 5  > summary(glm2)  Call: glm(formula = Survived ~ 0 + Pclass + Sex + Age, family = binomial(link = "logit"),      data = titanic_train)  Deviance Residuals:      Min       1Q   Median       3Q      Max   -2.7270  -0.6799  -0.3947   0.6483   2.4668    Coefficients:            Estimate Std. Error z value Pr(>|z|)     Pclass    -1.288545   0.139259  -9.253  < 2e-16 *** Sexfemale  5.056006   0.502128  10.069  < 2e-16 *** Sexmale    2.533875   0.456247   5.554 2.80e-08 *** Age       -0.036929   0.007628  -4.841 1.29e-06 *** --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  (Dispersion parameter for binomial family taken to be 1)      Null deviance: 989.81  on 714  degrees of freedom Residual deviance: 647.29  on 710  degrees of freedom   (177 observations deleted due to missingness) AIC: 655.29  Number of Fisher Scoring iterations: 5   And a summary of the resulting predictions:  > summary(predict.glm(glm1, newdata = titanic_test))    Min. 1st Qu.  Median    Mean 3rd Qu.    Max.    NA's  -3.5660 -1.9688 -0.5642 -0.3827  0.7782  3.1027      86  > summary(predict.glm(glm2, newdata = titanic_test))    Min. 1st Qu.  Median    Mean 3rd Qu.    Max.    NA's  -3.5660 -1.9688 -0.5642 -0.3827  0.7782  3.1027      86   if it simply reparamartarizes the model is there any advantage to having the intercept term or can I safely use the second model for increased interpretability?

I am running a binomial logistic regression with a logit link function in R. My response is factorial [0/1] and I have two multilevel factorial predictors - let's call them $a$ and $b$ where $a$ has 4 factor levels  $(a_1,a_2,a_3,a_4)$ and $b$ has 9 factor levels $(b_1,b_2,\dotsc,b_9)$. Therefore:  mod <- glm(y ~ a + b, family = binomial(logit), data=pretend) summary(mod)   The model output would then show all the information about the model as well as the coefficients.  There is a factor level for both a and b missing (a1 and b1) from the summary output. I understand that it is constrained in the "intercept" of the model. I have read that if I want to remove the intercept term and see the estimates for those factor levels I can just add -1 to the model formula, i.e.:  mod2 <- glm(y ~ a + b - 1, family=binomial(logit), data=pretend) summary(mod2)   In the new model (mod2) the intercept term is then gone and variable a's factor-level a1 is given amongst the list of coefficients. But, variable b's factor-level b1 is still missing and given that there is no intercept term anymore, how can I interpret the odds-ratio for that factor level then?  Could someone please explain to me how to get the coefficient for b1 too and why this is happening?


I have tried to upgrade 18.04 to 19.10 using command lines but there is one issue it's showing me is that:  Please install all available updates for your release before upgrading.   I have also tried for updates and it's showing it's up to date, now what I can do for upgrade my 18.04 Ubuntu to 19.10?

I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please?


What is the best practice for designing disabled states? In general disabled states cannot be interacted with.  Any opinions on presenting a tooltip/pop-up on hover or click when the user interacts with a disabled/greyed out link or button.

How many times did you use a desktop app or an online page and you come across one or more menu items which are disabled and you have no idea why its disabled. Using help or documentation is of no use. It gets frustrating because it's stopping you from moving forward.  I have NEVER seen this usability practice used. Hover over the disabled item and a tooltip lists you the reasons and you go "Oh.. ok. now I know". Your other option is you have to contact support or post in a forum, explain what you were doing. Wait for what possibly be days tell you get an answer, if any. This is the difference between black & white. Getting instant help by a simple hover or get frustrated and wait for hours.   If you are the one developing the app, you know exactly why an item is disabled because you disabled it in your code. So it's not hard to show the reasons to the user. Is it?  This little tip could have saved thousands of tech support calls. There are millions of posts on the web of Why something is disabled or grayed out.


I don't know if anyone can be helpful, but, I ve just received this 670$ fine from the NT.  I stayed for 3 days in Darwin and cracked one small firecracker, and got caught by the cops. (I know its very silly) Not saying that I wondn't mind paying the fine, but 670$ is a bit excessive isn't it? I'm leaving the country in 7 days and I literally have no money on me. What do you think would happen at the airport if I don't pay that fine?  Because I was just on holidays (WHV) I didn't have a permanent address though they sent it to my home in Europe.

I am from Canada, and I have been in Australia for 2 years on a working visa. I have received a fine ($110) for disturbing the peace (public nuisance). If I leave the country, can I get back in on a later date, on a tourist visa, if I haven't paid this fine?  If this is true, and I cannot get a tourist visa with an existing fine, can I pay it from outside Australia, and then apply for my tourist visa, hassle free?


Why do we use their instead of his in this sentence?     another driver flashes their lights

Is there a pronoun I can use as a gender-neutral pronoun when referring back to a singular noun phrase?  Each student should save his questions until the end. Each student should save her questions until the end.


Personal Opinion Example Badge: When I click on the  (Picture One) I can see percentage, but why not on this  (Picture Two)... generally new user are confused by seeing this... I think need positive record can be replaced with "Ratio" or "Number" as per as requirement with text, etc. for the user's convenience... Edit Example Model I want to replace (need positive question  record) text from (Picture Two) with Example as a => 0.1/0.5 positive question record ratio (like the Electoral badge shows 51/25 on question area) End Edit From this  (total questions - negative questions - closed - deleted)/total questions ≥ 0.5  Picture One  Picture Two

I was wondering about a question similar to  (for another site), where my "stats" are currently "10/5" (instead of "13/5"). The answer from "Shadow Wizard" links to , which links to yet another "". This last answer has some details about the actual calculation (like the "10" in my case), which is like so:  A positive question record means you don't have too many closed, downvoted or deleted questions, overall. The formula is (total questions - negative questions - closed - deleted)/total questions >= 0.5. Questions that have been downvoted and closed and deleted count three times in this calculation!  Somewhere I also read that these deleted questions seem to count for 3. But the OPer of a deleted question cannot see deleted questions anymore after a while (X days) either. So that seems to make it impossible to actually "verify" your own score (the "7" part), and also how many more "good questions" will be needed. In my case, I'm aware (remember) that there has been at least 1 question deleted. So I assume in my case the "7" must become at least "8" (I don't have negative or closed questions), though I doubt that will be sufficient. Also because I have 2 more questions with a zero votes balance (which makes me wonder also how accurate the "total questions" in the above quote really is ...). My suggestion: think of a way to somehow clarify (visualize) the formula quoted above. Or as a variation at least provide some way to find out the exact number of you questions that were ever deleted (not just the recently deleted ones). Or maybe some other type of indication to indicate "how much more good questions are needed to ever receive the "Curious" badge. Update: I recently learned about adding deleted:yes to a query. With that, these are some more stats about my questions (using "12345" to represent my user id from the site where this question is about):  user:12345 is:q - results in 14 (not deleted) questions, 11 of them have a positive (> 0) voting balance, none of these 14 are closed.  user:12345 is:q deleted:yes - results in 7 (deleted) questions, with this Status / Voting balance for each of them:       Question id Status Voting Balance     1 Closed +4   2 Duplicate +2   3 Migrated 0   4 Duplicate 0   5 Duplicate 0   6 Closed -1   7 Closed -4     So with that extra info, and as per the "Questions that have been downvoted and closed and deleted count three times in this calculation!" I think (guess) in my case the 2 deleted questions with negative voting balance corresponds to -(2*3)=-6 ... So that the "stats" in my case will have to become something equivalent to "(11-6)/5" = "5/5" ... Just guessing, and fingers crossed to see what will happen if I ever post a new question on that site that does not get downvoted+deleted (assuming all other votes for my existing questions don't change in the meantime).


Let R=End(V) be the ring of all linear endomorphisms of an infinite dimension complex vector space V with countable basis $\{e_{1},e_{2},...\}$ . Prove that R and RxR are isomorphic as left R-modules.

I was reviewing my homework and it seems I overlooked something crucial while proving some ring has no Invariant Basis Number property. This is exercise VI.1.12 in Aluffi's Algebra: Chapter 0  The setup: $V$ is a $k$-vector space and let $R = \mathrm{End}_{k}(V)$.   Prove that $\mathrm{End}_{k}(V\oplus V) \cong R^4$ as an $R$-module Prove that $R$ doesn't satisfy the IBN property if $V = k^{\oplus \mathbb N}$.   For the first, I used to the fact that $V \oplus V$ is both the product and coproduct (in $k$-Vect) of $V$ with itself to get the isomorphism. What I just realized is I only showed that the two are isomorphic as groups not $R$-modules. So what would be the $R$-module structure on $\mathrm{End}_{k}(V \oplus V)$?   For the second, I used the fact that $V = k^{\oplus \mathbb N}$ implies $V \cong V \oplus V$ which in turn implies $R = \mathrm{End}_{k}(V) \cong \mathrm{End}_{k}(V \oplus V)$. Again, I just realized that I only showed the latter two are isomorphic as groups.   It may be obvious (and maybe why my professor let it pass?) but I can't come up with a good $R$-module structure that makes the two group isomorphisms $R$-linear.  Edit:  Explicitly, these are the isomorphisms I'm dealing with. Let $\pi_j, i_j$ be the natural projection/inclusion maps of the $j$-th factor resp. and $\psi: k^{\oplus \mathbb N} \oplus k^{\oplus \mathbb N} \to k^{\oplus \mathbb N}$ the isomorphism given by $\psi(e_i, 0)=e_{2i-1}$ and $\psi(0, e_i)=e_{2i}$.  Then the first isomorphism $\mathrm{End}_k(V \oplus V)\to R^4$ is given by $\varphi \mapsto (\pi_1\varphi i_1,\pi_2\varphi i_1,\pi_1\varphi i_2,\pi_2\varphi i_2)$  The second isomorphism $R \to \mathrm{End}_k(V \oplus V)$ is given by $\alpha \mapsto \psi^{-1} \alpha \psi$  The composition doesn't seem to be $R$-linear if I use the obvious $R$-module structure on $R$ and $R^4$.


I'm learning awk. Trying to do something useful with it by listing all hidden files in ls's long format:  alias llh="ls -la | awk '{ if ( $9 ~ /^\./ ) { print $0 }}'"  This is resulting in an error, however:  awk: cmd. line:1: { if (  ~ /^\./ ) { print -bash }} awk: cmd. line:1:         ^ syntax error   The $9 isn't showing in the error output. Maybe because it's empty? So I tried:  alias llh="ls -la | awk '{ if ( $9 && $9 ~ /^\./ ) { print $0 }}'"  Still no luck.

When I create  alias wd='ps -ef | grep java | awk {'print $2 " " $9'} | egrep "(A|B|C|D)"'   or  function wd () {     ps -ef | grep java | awk '{print $2}' ... }   in my .bashrc file, I get errors.  Interestingly, if I source my .bashrc file with the function, it 'compiles', but when executing, gives me:   context is      >>> \ <<< {\print     missing }   Can someone help me with this, and also answer when its better to put something in a function versus in an alias?


This is a  about DoS and DDoS mitigation.   I found a massive traffic spike on a website that I host today; I am getting thousands of connections a second and I see I'm using all 100Mbps of my available bandwidth.  Nobody can access my site because all the requests time out, and I can't even log into the server because SSH times out too!  This has happened a couple times before, and each time it's lasted a couple hours and gone away on its own.  Occasionally, my website has another distinct but related problem: my server's load average (which is usually around .25) rockets up to 20 or more and nobody can access my site just the same as the other case.  It also goes away after a few hours.  Restarting my server doesn't help; what can I do to make my site accessible again, and what is happening?  Relatedly, I found once that for a day or two, every time I started my service, it got a connection from a particular IP address and then crashed.  As soon as I started it up again, this happened again and it crashed again.  How is that similar, and what can I do about it?


This problem is an example in a Discrete Math textbook. How can big-O notation be used to estimate the sum of the first n positive integers?  Solution: Because each of the integers in the sum of the first n positive integers does not exceed n, it follows that $$1+2+...+n \le n+n+...+n=n^2$$ From this inequality it follows that $1+2+...+n$ is $O(n^2)$.  I do not understand how the sum of $n$'s is equal to $n^2$. Can anyone explain to me what the book used to get this?

In my text, I am given that the sum of the first n positive integers can be understood in terms of big-O notation.   ''Since each of the integers in the sum of the first $n$ positive integers does not exceed $n$'', we can write:  $$1 + 2 + \cdots + n \leq n + n \cdots + n= n^2$$  Why does $n + n +\cdots + n = n^2$ ?


I answered 39 questions out of which 9 are zero score accepted answers.  Why did I am not awarded the Tenacious badge?

Just curious whether the process takes a while, and whether it scrapes through history to determine if it was once valid or not. Currently, I have 6 0-vote accepted answers and 20 1+-vote answers (), and that makes it > 5 and > 20% but not for long if voting goes up or down from here. ;-P  Update:  Special thanks to Grace Note for pointing out the  to follow. I upgraded this to a bug because it's been 48 hours during which the criteria supposedly were met. 6 0-votes, 20-23 1+ votes during the whole period. The criteria only last so long, so it may go out of scope soon. If it only checks every 3 days, I'm not sure if that's intentional or a bug.


Let $P_n$ be the $n$th prime. Ie $P_1 = 2, P_2 = 3, P_3 = 5, ...$ Show that $P_n \le 2^{2^n}$   Induction seems to be useless here. Is there a hint someone can provide?

Prove that $\forall n \in \mathbb{N}^*, P_n \lt 4^n$ where $P_n$ is the $n$th prime number. I'm searching for a proof that doesn't use induction and uses only the elementary concepts of number theory.  This theorem appears in an old french book on Arithmetics destined to high school level students (lycée). It is introduced right after the concept of decomposition into prime factors. The book includes a proof that I didn't understand. You can see below a screenshot taken from the book and a translation attempt.   Theorem For all integers $n \gt0,$ the $nth$ prime number $q$ verifies the inequality $q \lt 4^n$.   Demonstration The $[1,q]$ interval is included in the set of integers $k$ that can be written, (after grouping all the squares that can be formed with the $n$ prime numbers $p_i  \le q $ in a decomposition of $k$), as $k = m^2p_1^{e_1}p_2^{e_2}...p_n^{e_n}$ with $e_i \in {0,1}$. (Here, $p_i$ is the i-th prime number, and $p_n = q$.). There are no more than $\sqrt{q}$ integers like m, and at most $2^n$ choices for the exponents $e_i$, what shows that $q$, cardinal of this set, is strictly lower than the product $2^n\sqrt{q}$, then the result.


I'm working on a bash script that appends to /etc/profile but instead of appending, I accidentally wrote over it, losing all of its content. How can I restore the file?  I did search here but being new to Ubuntu, I don't know if the posted /etc/profile content I see in other questions is the default content.

I would like to restore LightDM to its default state, because for some reason /etc/lightdm/unity-greeter.conf is now an empty file.  Deleting /etc/lightdm/unity-greeter.conf and then running sudo apt-get install --reinstall unity-greeter doesn't create a new config file as you might expect.   How can I restore a missing config file?


On Ubuntu 12.04, how can I find out    when an application was installed and  when the applications/libraries it depends on are installed/upgraded/updated?   My Okular doesn't work any more. I guess it might be because something it depends on has been upgraded.

How can I list installed packages by installation date?  I need to do this on debian/ubuntu. Answers for other distributions would be nice as well.  I installed a lot of stuff to compile a certain piece of code, and I want to get a list of the packages that I had to install.


I'm writing my thesis with the following format: My problem is that the references are not appearing in the correct, I'm having my first ref to be cited as 11 instead of 1! Although in the bibliography at the end it is shown in the correct order..  \documentclass[letter, onecolumn, 12pt] {report} \usepackage{setspace} \usepackage[numbers,sort&compress]{natbib} \usepackage{algorithm2e} \usepackage{multirow} \usepackage{float} \newtheorem{lemma}{Lemma}  \newtheorem{prob}{Problem} \newtheorem{corollary}{Corollary} \newtheorem{question}{Question} \newtheorem{conjecture}{Conjecture}  \newenvironment{proof}{{\bf Proof.}}{\hfill\rule{2mm}{2mm}}  \newenvironment{remark}{\begin{remarka}\rm}{\end{remarka}}  \newtheorem{axiom}{Axiom}[section] \newtheorem{defn}{Definition}[section] \newtheorem{thm}{Theorem}[section] \newtheorem{rem}{Remark}[section] \newtheorem{prop}[thm]{Proposition} \input{head.tex} \begin{document} \onehalfspacing \maketitlepage  \pagenumbering{roman}  \setlength{\parskip}{.25cm}   EVERYTHING GOES HERE THE ABSTRACT AND CHAPTERS   \bibliographystyle{ieeetr} \bibliography{JETCAS_2014_v2} \end{document}

I am having an issue with LaTex/Bibtex presenting my citations in order of appearance. I know there a plenty of questions on this and I have read some of them, but the solutions posted don't seem to do me any good. I am using MacTeX and TeXmaker.  I am writing a large document, like a Thesis. Chapters are split between individual Tex files and included using the \include command.  I have a large .bib file that is maintained by Mendeley (program I use for storing my references and producing a BibTex file).  I am using the package, cite (mainly for doing references like [1-3,6,9])  I have a pretty standard looking document.  \documentclass[11pt,a4paper]{report} \setcounter{secnumdepth}{3} \setcounter{tocdepth}{3} \newcommand{\doubleSignature}[3][Alex Mason]{% \parbox{\textwidth}{ \centering #3 \today\\ \vspace{2cm}  \parbox{7cm}{   \centering   \rule{6cm}{1pt}\\    #1  } \hfill \parbox{7cm}{   \centering   \rule{6cm}{1pt}\\   #2 } } } \usepackage[utf8]{inputenc} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} %\usepackage[sorting=none]{biblatex} %\bibliography{Alex} % Where journals.bib and phd-references.bi \usepackage[pdftex]{graphicx} \usepackage{enumerate} \usepackage{nomencl} \usepackage{wasysym} \usepackage{booktabs} \usepackage{cite} \usepackage[left=1in,right=1in,top=1in,bottom=1in]{geometry} \graphicspath{{./Diagrams/}} \usepackage[labelfont={sf,bf}, margin=1cm]{caption} \usepackage{subcaption} \renewcommand{\figurename}{Fig.} \renewcommand{\tablename}{Tab.} \renewcommand{\bibname}{References} \author{NAME (MEng)} \title{TITLE} \date{\today} \makenomenclature %------------------------------------------------ \begin{document} \maketitle \pagenumbering{roman} %-----------------------------------------------certificate of originality----------------      -------------------------------------------- \input{CertofOrigin} \begin{abstract} ABSTRACT \end{abstract} %-----------------------------------------------contents------------------------------------------------------------ \tableofcontents \listoffigures \addcontentsline{toc}{chapter}{List of Figures} \listoftables \addcontentsline{toc}{chapter}{List of Tables} \chapter*{Acknowledgements} \addcontentsline{toc}{chapter}{Acknowledgements} ACKNOWLEDGEMENTS \printnomenclature[1.5in] \addcontentsline{toc}{chapter}{Nomenclature} \pagebreak \pagenumbering{arabic} \include{2ndYearReport_CHAP1} \include{2ndYearReport_CHAP2} \include{2ndYearReport_CHAP3} \bibliographystyle{unsrt} \bibliography{Alex} %\printbibliography \end{document}   The goofy looking part at the top (\newcommand{doubleSig.....) is just for when i input a special page I made containing a certificate of originality spiel with two boxes for signatures and my university logo.  As you can see I am using the standard bibtex way of doing bibliographies by stating the style then the stating the bib file to use right at the end of the document. I have tried biblatex but can't get it to work. It says it hasn't produced the bib file but doesn't really state why.  As far as I am aware everything was working A-OK until I started on the second chapter and began adding citations in there. Now my citations are all messed up and won't correct. My first citation starts with [9]!!!  [1] appears in a figure caption later down the page, after 10, 11 and 12 have been called!  I have tried deleting all the working files (bbl, aux, log etc) but nothing happens. I get the same result. IIRC I used to have this problem with MS Word and is part of the reason why I switched to LaTex...yet it seems to have followed me!   bibtex does through a few warnings when it runs stating that some references are missing journal names or volume numbers. Would that be a reason?  What have I done wrong with my code?


I have read in several sources that in agreement with a negative statement one can use either, for instance:     I am not a child, and my cousin isn't either.   At the same time, there is the word neither that can be used here:     I am not a child, neither is my cousin.   From the sentences aforementioned, which one sounds more natural? Which is more formal/informal? Is there any difference at all?

I would like to make sure I understood the usage of these:  Do you want A or B?        I do not want either. [none of them]     I want neither. [Can I say that?]


In many movies and TV series blue background is being used for giving special effects or for some kind of animations. So what makes blue color so special? Which is better, blue or green backgrounds?

I remember reading that green colour makes the best contrast with colour of human skin so in post editing it is easier to remove it.   Is that the only reason why they use green backgrounds when filming movie scenes? I would think that different skin colour would contrast differently against green background, which would invalidate this theory.


When I attempt the install, my mouse freezes as soon as I select the install option.  I can get through the process using the keyboard, but, the system hangs at "Configuring boot loader...".  Any suggestions?  Thanks, H

I'm thinking about installing Ubuntu Desktop, but I don't know what flavor is the best for my system. What are the minimum and recommended hardware requirements? What kind of CPU? How much memory? Should I have Hardware Acceleration? What flavor should I use?  This is an attempt of a canonical answer. My answers have the "official  requirements", the recommended are a mix of official sources and opinion based (along with the answer it's told the source). You can comment or edit if you feel that the information is obsolete or incomplete. It is a good rule of thumb that any system capable of running Windows Vista, 7, 8, x86 (Intel) OS X will almost always be a lot faster with any Ubuntu flavor even if they are lower-spec than described below.


If you don't get the question, that's exactly what I want to know.  Imagine we have a ordered list of fruits.  ["Apple", "Banana", "Peach", "Orange"]   I want the 3rd fruit in that list. But you don't know which one I want. How one asks which member in the sequence I want.  like:     What nth fruit do you want?   Now, I know that this is wrong. I'm looking for the right expression to ask this. I hope my question is now clear.

How to ask the position(?) of a president (like 10th) of a country, correctly?


I am very new to LyX or LaTeX, so I do not want to complicate the process. So what I currently do, is saving the figure as a PDF and then attaching it. But I don't think this is a good method as the output I am getting looks like this:  Is there any easy way to do this? The settings are as follow: Placement: Here Definitely Alignment: Center

I am preparing image files to be included in a latex document. The image file is generated by printing a Matlab plot.   If I print the plot in eps format, the content of the eps file is fully occupied with the plot;   if I print the plot in pdf format, then there are big margins above and below the plot in the pdf file;   if I use ps2pdf to convert the eps file into a pdf file, the big margins will be added above the plot.   I would like to use pdflatex, so I prefer pdf format of image files. I was wondering how I can save the plot in pdf format without the big margin above and below the plot?


I have two table like by following   #Table1 Vid  Sid 1     1 1     2 2     3 2     4 3     5 4     6   and  #Table2 Sid  SValue 1    Value1 2    Value2 3    Value3 4    Value4 5    Value5 6    Value6   And I need the output by following like this..  #Output Vid SValue 1   Value1,Value2 2   Value3,Value4 3   Value5 4   Value6   Need SQL Query for the above ouput..

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


I was reading a little from a book on Real Analysis (which I'm not that far into yet), and I came across a problem: prove $2^n \ge n^2, \forall n >4\in \Bbb N$. Though "challenging", I was able to prove this problem with induction without much struggle. I then considered proving this same problem for any integer '$a$' in replace of $2$. I.e. prove:  $$a^n \ge n^a$$  where $a,n \in \Bbb N$. The first thing I decided to do was look for the smallest '$n$' that would actually work for a given '$a$'. I did this by simply solving for $n$:  $$\begin {align} a^n \ge& n^a\\ n^{1 \over n} \ge& a^{1 \over a}\\ {1 \over n}\ln n \ge& \ln a^{1 \over a}\\ \ln n e^{-\ln n} \ge& \ln{a^ {1 \over a}}\\ -\ln n e^{-\ln n} \ge& -\ln{a^ {1 \over a}}\\ -\ln n \ge& W_0(-\ln{a^{1 \over a}})\\ n \ge& e^{-W_0(-\ln a^{1 \over a})} \end {align}$$  where $a \in \Bbb N$ and $W_0(x)$ is Lambert's $W$ Function.   My first question is: "Is this a valid constraint to put on $n$?", and my second and third questions are: "Is this a valid method for proving the inequality for values of $n$ larger than or equal to what I just derived? And if it isn't, how do I prove it using induction?"

How to find the minimum of $n$ when we know $a$, to satisfy:  $a^n<n^a$  $a^m>m^a$  for each $m>n$  $n$ and $m$ are natural numbers.


I have a huge list and want to make a list of lists from it. For example: [2,3,4,5,6,2,8,9,11,10]------> [[2,3],[4,5],[6,2],[8,9],[11,10]]  How can I achieve that in Python?

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


I want run a process on at a specific time (4:00 AM).  Here is my code:  if(Current time == 4:00) {     ProcessStartInfo autorestart = new ProcessStartInfo(@"C:\Autostart.bat");     autorestart.UseShellExecute = false;     SecureString pw = new SecureString();      pw.AppendChar('p');     pw.AppendChar('a');     pw.AppendChar('s');     pw.AppendChar('s');     pw.AppendChar('w');     pw.AppendChar('o');     pw.AppendChar('r');     pw.AppendChar('d');      autorestart.Password = pw;     autorestart.UserName = "support";     Process.Start(autorestart); } else {     MessageBox.Show("Time not same"); }

I have a service written in C# (.NET 1.1) and want it to perform some cleanup actions at midnight every night. I have to keep all code contained within the service, so what's the easiest way to accomplish this? Use of Thread.Sleep() and checking for the time rolling over?


Pretty much the title. Here's some screenshots:  Object mode:   Edit mode:   Luckily I'm done and it still exports like normal. What caused this? Is there a fix?

I have append a mesh (rex) from this .blend .  In edit Mode I see different vertices from objcet mode (see pictures). The vertices of belt are missing!  OBJECT MODE:   EDIT MODE:   How can I edit vertices of belt? Is It a bug?  This is my .blend  maybe can help.


$\frac{1}{99989999} = 1.00010002000300050008001300210034005500890144... \times 10^{-8}$    (), which includes the Fibonacci sequence $(1\ 1\ 2\ 3\ 5\ 8\ 13\ 21\ 55\ 89\ 144\ldots )$.  This is fascinating to me but I can't figure out how this works, and a Google search doesn't seem to reveal anything.


Why does the following not compile:  typedef int Table;  class FullObjId  { public:     explicit FullObjId( const Table* i ) {} };  class TableInfo  { public:     TableInfo( const FullObjId& o ) {}     bool isValid() { return true; } };  void dataSourceForHist( const Table& table ) {    // The next line gives an error    TableInfo tableInfo( FullObjId( &table ) );    // Unless it's written like this:    //TableInfo tableInfo( ( FullObjId( &table ) ) );     if (!tableInfo.isValid())    {       ...    } }   I have tried with the Intel Compiler 12.1 for Linux, and using  with g++ 4.8, icc 13.0, clang 3.4.1. All the compilers I have tried give an error along the lines of:  error: request for member ‘isValid’ in ‘tableInfo’, which is of non-class type ‘TableInfo(FullObjId&)’

As a  developer I'm used to running through constructors:    class Test {     public Test() {         DoSomething();     }      public Test(int count) : this() {         DoSomethingWithCount(count);     }      public Test(int count, string name) : this(count) {         DoSomethingWithName(name);     } }   Is there a way to do this in C++?  I tried calling the Class name and using the 'this' keyword, but both fail.


I was solving a few problems from a textbook and I came across this one:     Find the tangent lines to the graph of $x^2+4y^2 = 36$ that go through   the point $P=(12,3)$   I could find the tangency points $$ but my solution was completely messy (I had four equations that I had to go back-and-forth with.  Is there an elegant/simple solution to that?  Tangency points:  $$P_1 = (0,3)$$ $$P_2 = \left( \frac{24}{5} , 3-\frac{24}{5} \right)$$

I ran into a problem I have no idea how to begin, maybe you guys can help me out. I think maybe it has something to do with parametric equations? But this is just a guess.  Find equations of both the tangent lines to the ellipse $x^2 + 4y^2 = 36$ that pass through the point $(12, 3)$. I can easily find the derivative using implicit differentiation, but what is meant by two tangent lines?


I have a php web page with a header on it. Inside the header I have a logo, and a nav tag with links, and a login form in it. The only problem is that everything in the nav is aligned at the top of the header. Is there a way to center all of it inside the header? I have tried properties like vertical-align: middle and nothing has worked. I have looked at other questions and tried to implement it, but nothing has worked so far.    body {   margin: 0;   background: #555;   font-family: 'Work Sans', sans-serif;   font-weight: 300; }  .container {   width: 80%;   margin: 0 auto; }  header {   background: #55d6aa; }  header::after {   content: '';   display: table;   clear: both; }  .logo {   float: left;   height: 40px;   width: 40px;   padding: 0;   margin: 0; }  nav {   float: right;   display: flex; }  nav div{   display: flex;   float: right; }  nav a {   color: #444;   text-decoration: none;   text-transform: uppercase;   font-size: 16px; }

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           <form action="includes/login.inc.php" method="post">
<input type="text" name="mailuid" placeholder="Username/Email">

<input type="password" name="pwd" placeholder="Password">

<button type="submit" name="login-submit">Login</button>
           </form>

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           <form action="includes/logout.inc.php" method="post">
<button type="submit" name="logout-submit">Logout</button>
           </form>

       What I want:

I have a div with two images and an h1. All of them need to be vertically aligned within the div, next to each other. One of the images needs to be absolute positioned within the div. What is the CSS needed for this to work on all common browsers?

testing...


Yesterday, all of a sudden I started getting "Activation required" on my iPhone5 due to which I just can not login even when I enter my Apple credentials. Exactly this problem - .  Trying to follow  to solve it but I just can not get it into DFU mode .    - "While pressing and holding the Home button down, connect the USB cable to the iPhone, iPad, or iPod touch. The device should turn on." - The iPhone does not turn on for me :-/  How do I install 7.2 which has the bug fix?

My iPhone 5 that has been running iOS 7 since beta 1 suddenly wants to be activated.  When locked, it shows me my wallpaper. After sliding to unlock, it asks for my passcode. When I enter it, it takes me straight to the 'Activate iPhone' page - like it wants to be set up.  The text on the page:     This iPhone is currently linked to an Apple ID (e**@icloud.com). Sign in with the Apple ID that was used to set up this iPhone.   After I input the correct credentials and press Next in the top right corner, the title of the page changes to 'Activating...', then changes back to how it was before.  About 15 seconds later, it transitions to a 'Could not activate iPhone' page:     Your iPhone could not be activated because the activation server is temporarily unavailable. Try connecting your iPhone to iTunes to activate it, or try again in a couple of minutes.      If this problem persists, contact Apple Support at apple.com/support   Has anyone encountered this problem before? Is there a solution to it?


I recently installed Ubuntu 12.04 LTS on my Dell D430 to replace an old version of Ubuntu. Now the wireless is not working. I have looked at a lot of the posts on the web and tried the suggestions to no avail. Can anyone give me a start? I tried using Synaptic and by using the help on the following links    and also looking at the blacklist.   Any help would be appreciated!

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


I want to make the curtain looks like its giving the cube a way to pass through the curtain i made from a plane My question is, how and what step should i take to make the curtain that way?

I have two chairs, a cloth piece falling on it and then a helmet falling above the cloth on one of the chairs. Whatever the setting I'm trying I cannot get the helmet fall nicely on the chair and interact naturally with the cloth. Right now I have following:    the helmet is falling down  the cloth is falling down  the cloth is interacting with the chairs naturally  in the process of falling the helmet gets pushed by the cloth piece far away (as if it would be very hard surface).       I also read that soft body physics might be a solution, but it didn't work in my case and the rendering times are getting expanded.  The cloth has settings: 5/M, 10/s, 15/b, (here I tried almost everything) rigid body is off,  Collision physics is off  Helmet settings:  Right body active, mass 10, all other physics are off.  Right now almost all the other settings (except cloth physics) are default.  Would be glad to get some help!    Edit : Amended the Rigid Body Collision shape to 'Mesh' and this helped with allowing the helmet to collide with the cloth but now the cloth is being forced through the chair.


According to Han Solo, Luke has tried      To train a new generation of Jedi, but fled after one of his students turned to the dark side.  That would be Ben Solo.     I’m wondering      Who were the other students? Are any of them still alive?     My question is, is there any evidence of Jedi      other than Ben Solo? (and of course Luke Skywalker; I'm excluding 'force-sensitive' non-Jedi like Maz Kanata. I'm specifically talking about the remainder of Luke's trainees, or survivors of the Old Republic).      Note - I don't believe this is a duplicate of  as the scope includes non-trainee Jedi.

In the film, Han says:     “He was training a new generation of Jedi. There was no one else left to do it, so he took the burden on himself. Everything was going good, until one boy, an apprentice, turned against him and destroyed it all. Everything Luke had worked toward: gone. Luke felt responsible. He walked away from everything.”   So what became of this "new generation of Jedi?"  The way Han phrases it, it is pretty clear that the betrayer was not the only apprentice.  Even if they never completed their training, where are there other people that      learned the ways of the Force from Luke?


Find all instances on a 24 hour analog clock where if the hour and minute hands are interchanged we get a valid time.    Solution:  Let the position of the hour and minute hands be measured clockwise in degrees from the vertical.  Let:       X  =  position of hour hand    24X  =  position of minute hand  (mod 360)     After interchanging the hour and minute hands:    24X  =  position of hour hand    (mod 360)    576X  =  position of minute hand  (mod 360)  =  X    We seek all solutions to:       X  =  576X (mod 360)       0  =  575X (mod 360)       X  =  (360/575)N; N  =  0, 1, 2, …, 574

At 12 o'clock, the hour hand and minute hand of the clock can be swapped, and the clock still gives the same time, but at 6 o'clock, it can not be swapped. So in what cases when we swap the hour and the minute hand position does a clock still give a valid time?


I have this logic in a ksh script on AIX 6.1 and it works fine.  integer loop_count=0 integer sleep_interval=5 integer alarm_interval=60 if (( $loop_count*$sleep_interval%$alarm_interval -eq 0 )) then     echo "hello" else     echo "bye" fi   On AIX 7.1 is gives me this error.     line 4:  *5%60 -eq 0 : arithmetic syntax error   If I change it to   if (( $sleep_interval*$loop_count%$alarm_interval -eq 0 ))   so the variable that could be zero is not first, it works fine.  Many other ways to fix it as well, but it's curious to me that the logic that was valid in 6.1 fails in 7.1.

I have a ksh93 script that I'm migrating from AIX 6.1 to AIX 7.1  It's failing on 7.1 but works fine on 6.1.  Here's a snippet of the important parts.  integer f_count=0    . . .     . . .     . . .  if [[ ($f_count*$sleep_interval%$alarm_interval -eq 0 ) && $f_count > 0 ]]        then   When it hits the "if" I get  line 191: *10%300: arithmetic syntax error  I decided to simplify it by typing this at the command prompt.  AIX 7.1> integer x=1           AIX 7.1> [[ $x*10%300 -eq 0 ]] AIX 7.1> print $? 1 AIX 7.1> integer x=0           AIX 7.1> [[ $x*10%300 -eq 0 ]] -ksh93: *10%300: arithmetic syntax error   AIX 6.1> integer x=1           AIX 6.1> [[ $x*10%300 -eq 0 ]]  AIX 6.1>  print $?                                                                                1 AIX 6.1>  integer x=0                                                            AIX 6.1>  [[ $x*10%300 -eq 0 ]]  AIX 6.1>  print $?                                                                                0   To show it's ksh93 on AIX 6.1 I did this.  asdlkfjasd -ksh93: asdlkfjasd: not found.   If I move the 0 value so it's not first, it works as expected.  AIX 7.1> integer x=1             AIX 7.1> [[ 10*$x%300 -eq 0 ]]   AIX 7.1> print $?              1 AIX 7.1> integer x=0            AIX 7.1> [[ 10*$x%300 -eq 0 ]]   AIX 7.1> print $?              0   This will fix my issue as I know the 2nd and 3rd variables in my original equation will never be 0.  Is this showing an AIX 7.1 bug?


How can I make copy/paste in the Ubuntu 16.04 Shell? For example, pasting a string from my browser to the cli and execute it as a command (Ctrl+V not working by default)

When trying to copy and paste from the terminal, it doesn't work. I can't use Ctrl + C to copy, and when I select the text with the mouse and right click, no option to copy or cut appears. I installed Ubuntu 12.04 for the first time a few days ago and maybe it is missing something. Copy and paste does work in LibreOffice.


The meshes clump together when subdivided:    The origin is off of the face:

I am currently trying to develop my modeling skills, and following a tutorial found on YouTube. The tutorial teaches how to create an anvil. At 19:10 or so into the video, a subdivision surface modifier is used to create a smooth, soft look.  However, when I do the same, mine looks very sharp and generally bad.  Any ideas why? I will include the blend file below, I appreciate your time and suggestions.    This is his when he subdivides, which is very different from mine when I do the same at the same settings. (I cannot post more pictures because I am new, but if you check the blend file I attached, you should be able to see the difference.   This is what it looks like when I subsurf without the base face.


I am looking for an overview of file formats that can store geo-referenced 3D geometries. There are no further requirements such as texture support, etc.  I have found the following formats so far and seek extensions to that list:   Shapefile GML KML/KMZ GeoJSON

I am looking for a simple georeferenced 3D-data format to store very simple building models. Each building should be represented as a number of poylgons, semantics do not matter. It would be ideal if this format is readable via ArcGIS, but that is not an absolute requirement.  I know there is GML/CityGML but I am looking for something simpler that ideally has either a JSON or XML serialization.


Is there a name in photography postprocessing for this kind of look?      How can it be achieved?  There are other photos of this sort, but I can't find them right now.

I searched over the web but all pages offers solutions via Photoshop. Is there a way to do it in lightroom or is PS the only solution? I'd think something like levels would help, but there are no levels in LR, or am I missing something?


The help pages in R assume I know what those numbers mean, but I don't. I'm trying to really intuitively understand every number here. I will just post the output and comment on what I found out. There might (will) be mistakes, as I'll just write what I assume. Mainly I'd like to know what the t-value in the coefficients mean, and why they print the residual standard error.   Call: lm(formula = iris$Sepal.Width ~ iris$Petal.Width)  Residuals:      Min       1Q   Median       3Q      Max  -1.09907 -0.23626 -0.01064  0.23345  1.17532    This is a 5-point-summary of the residuals (their mean is always 0, right?). The numbers can be used (I'm guessing here) to quickly see if there are any big outliers. Also you can already see it here if the residuals are far from normally distributed (they should be normally distributed).  Coefficients:                  Estimate Std. Error t value Pr(>|t|)     (Intercept)       3.30843    0.06210  53.278  < 2e-16 *** iris$Petal.Width -0.20936    0.04374  -4.786 4.07e-06 *** --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1    Estimates $\hat{\beta_i}$, computed by least squares regression. Also, the standard error is $\sigma_{\beta_i}$. I'd like to know how this is calculated.  I have no idea where the t-value and the corresponding p-value come from. I know $\hat{\beta}$ should be normal distributed, but how is the t-value calculated?  Residual standard error: 0.407 on 148 degrees of freedom   $\sqrt{ \frac{1}{n-p} \epsilon^T\epsilon }$, I guess. But why do we calculate that, and what does it tell us?  Multiple R-squared: 0.134,  Adjusted R-squared: 0.1282    $ R^2 = \frac{s_\hat{y}^2}{s_y^2} $, which is $ \frac{\sum_{i=1}^n (\hat{y_i}-\bar{y})^2}{\sum_{i=1}^n (y_i-\bar{y})^2} $. The ratio is close to 1 if the points lie on a straight line, and 0 if they are random.  What is the adjusted R-squared?  F-statistic: 22.91 on 1 and 148 DF,  p-value: 4.073e-06    F and p for the whole model, not only for single $\beta_i$s as previous. The F value is $ \frac{s^2_{\hat{y}}}{\sum\epsilon_i} $. The bigger it grows, the more unlikely it is that the $\beta$'s do not have any effect at all.


I was given an exercise to show $A=\frac{\mathbb{C}[X,Y]}{(X^2+Y^2-1)}$ is a PID. But I wonder if it is at all true. Note that PID $\implies$ UFD. But we have $$X\cdot X = 1-Y^2 =(1-Y)(1+Y)$$ in $A$ which contradicts UFD.     Is there something wrong in the above factorization? Any suggestions / hints.   Edit: I can prove mechanically it is PID. My main concern was the above factorization. Thanks for the comments.

Prove that the quotient ring $\mathbb{C}[x,y]/(x^2+y^2-1)$ is a unique factorization domain.   I am trying to prove first it is a principal ideal domain. However I am really stuck on this problem


Problem  I get a PDO syntax error when running a PDO statement where the table name is parametrized, like in  $sql = 'DELETE FROM :table_name'; $query = $this->db->prepare($sql); $query->execute(array(':table_name' => "mytable"));   I could reproduce the problem with SELECT etc., so it's a general issue. I tried to write it with backticks, with database name in front of it, a combination of both etc, nothing works.  Question  How to do this ?

Why can't I pass the table name to a prepared PDO statement?  $stmt = $dbh->prepare('SELECT * FROM :table WHERE 1'); if ($stmt->execute(array(':table' => 'users'))) {     var_dump($stmt->fetchAll()); }   Is there another safe way to insert a table name into a SQL query? With safe, I mean that I don't want to do  $sql = "SELECT * FROM $table WHERE 1"


I am trying to make a simple flag animation with Blender then export it to Unity3D. I already made the flag in blender with a wind force and the flag works well in Blender.  However I am not sure how to create an animation out of the flag with the wind force and export that animation to Unity3D.

I'm trying to understand which animations on blender will be able to be animated in unity.  I have tried animating a net in such a way that when the ball hits it I will activate the animation to look realistic- I built a net, added a lattice modifier and animated with this lattice, but then I saw the posts about Unity not able to run them.  So figured I'll try Cloth animations but then I saw posts says Unity wont accept those animations also.  So, beside manually moving each individual vertex on my net, how can I animate that?


I need to export color orthophoto map to gray scale geotiff file using free tools (like qgis) any idea?  I tried qgis preview but this does not produce new geotiff file

I suspect that there exists a gdal tool (gdal_translate?) that will convert a 4-channel PNG (+ world file) to a 1-channel (gray-scale) geoTIFF.  From the gdal_translate man page, it appears simple to go in the other direction, i.e. to expand a monochrome raster to a 3 or 4-channel image, but I can't figure out how to go from many channels to one.  If not gdal (hardly conceivable), then another *nix command-line tool?


is there any 100% working method to update openssl to the non vulnerable version on Debian Wheezy. I do not want to upgrade the whole OS, nor would I like to install a non official package.  Is there any solution right now ?  Thanks

This is a  about understanding and remediating the Heartbleed security issue.   What exactly is CVE-2014-0160 AKA "Heartbleed"? What is the cause, what OSs and versions of OpenSSL are vulnerable, what are the symptoms, are there any methods to detect a successful exploit?   How can I check to see if my system is affected? How can this vulnerability be mitigated? Should I be concerned that my keys or other private data have been compromised? What other side effects should I be concerned about?


Sun attracts earth by gravitation. And similarly every heavenly body attracts others. But why are they rotating? The sun is moving in ellipse in the galaxy, the earth is rotating and revolving and same for other planets. Why aren't they stationary?

The origin of spin is some what a puzzle to me, everything spin from galaxies to planets to weather to electrons.  Where has all the angular momentum come from? Why is it so natural?  I was also thinking do photons spin? we always think of the wave as a standard 2d sin wave but could this rotate in 3d? What implications would this have?   And what about spacetime how does all the spinning effect?  This has always been avoided in all lectures and classes I ever went to.


The following code converts the float type  7.5 to an integer value 7, the remainder is lost. Here, the typecasting operator is int. I know it is valid typecast in C++.   int main() {         int i;         float f = 7.5;         i = (int) f; // Valid in C/C++ }   But another way to do the same thing in C/C++ is to use the functional notation preceding the expression to be converted by the type and enclosing the expression between parentheses:  i = int (f); // It is worked in C++ but not C   So, I have a question, Is it valid way to typecast in C++?

What are the proper uses of:   static_cast dynamic_cast const_cast reinterpret_cast C-style cast (type)value Function-style cast type(value)   How does one decide which to use in which specific cases?


The phrase "May the force be with you" does not exclusively belong to the Jedi. But members of the dark side seem to be reluctant in saying "May the force be with you/us" to each other. Why? Don't they want the force to be with them?

This saying/blessing seems to me just as applicable for someone allied with the Dark Force as a Light Force ally as the statement appears to be Force-neutral. By Dark Force user, I mean it (or similar words) being said in the business of Dark Force-leaning activity, not someone who may have said it as a Light Force user and then went to the Dark Side (and never said afterwards).   Either Canon or Legends examples are acceptable.


If a charged particle is projected under the influence of magnetic field, magnetic force acts perpendicularly with both the direction of magnetic field and velocity of particle. The direction can be calculated by vector product rule.                    But, my question is that why does the force act normally to both the direction? In other words, what is the physical explanation of the statement "magnetic force is vector product of velocity of charged body and magnetic field"?

The Lorentz force on a charged particle is perpendicular to the particle's velocity and the magnetic field it's moving through. This is obvious from the equation:  $$ \mathbf{F} = q\mathbf{v} \times \mathbf{B} $$  Is there an intuitive explanation for this behavior? Every explanation I've seen simply points at the equation and leaves it at that.  I can accept mathematically why $\mathbf{F}$ will be perpendicular to $\mathbf{v}$ and $\mathbf{B}$ (assuming the equation is correct, which it is of course). But that doesn't help me picture what's fundamentally going on.  Trying to create an analogy with common experiences seems useless; if I were running north through a west-flowing "field" of some sort, I wouldn't expect to suddenly go flying into the sky.  I'm hoping there's a way to visualize the reason for this behavior without a deep understanding of advanced theory. Unfortunately, my searching for an explanation makes it seem like something one just has to accept as bizarre until several more years of study.


Novice in Blender, sorry:)  Why do I have this view of chimney on the house?   I've extruded the hollow region. On the video tutorial that I followed, everything is ok with chimney view  What may be the problem?

I was following  on creating a watch and noticed that when I rendered the watch, some pieces were messed up.  I'm new to 3D modeling and I've just learned Blender, I can't explain it well, so here's a picture:    Other examples:     I don't know if it's a problem with my World texture, the object, or the object's texture/material, so I can't even guess how to fix it. What causes this? Is it possible to fix it?


Recently acquired new parts to build my second custom computer, primary focus of gaming. Looking into a new OS I just can't justify buying Windows 10. I tried downloading Ubuntu on my current computer but it requires a certain reader that I don't have. ubuntu-16.04.1-desktop-amd64.iso is the name of the file. Standardized disc image stored in ISO-9660 data format – contains complete disc file structure, including files, file attributes, and boot code. That's the description I get so maybe it's because I'm on a computer with an OS already installed it won't run? So a few questions from someone who only knows that Ubuntu is an OS:  How do I go about putting Ubuntu onto a flash drive from my current computer and then installing that onto my new computer? Doesn't the new computer need that reader as well? Any guidance regarding installation and making sure it runs reliably is appreciated.    Any tips for a brand new user of Ubuntu who has no experience and has only dealt with Windows?    Thanks for taking the time to read my comment, even if your answer is a link to a helpful thread that would be really appreciated.   Edit 1: I have one 500gb SSD, Samsung EVO 850 to be specific, no HDD or second hard drive.    Edit 2: My "new" computer is one that I have to put together and build myself with 1 blank, 500gb SSD. It does not have an OS on it, How would I go about putting Ubuntu onto the SSD? Would I get a bootable USB and download the files from there onto my SSD? Then choose to boot from my SSD? I am currently using my "old" computer which is running Windows 7.

I would like to see a full how-to guide on how to install Ubuntu.


I'm from India and have applied for a Belgian Resident Permit. I received a Form 2, but have yet to receive the actual permit. Can I travel for a few days to some other Schengen county ?

I googled all over and couldn't find a definitive answer on this. I arrived to Poland on a Schengen visa and applied for a temporary residence permit on my 88th day in the Schengen area. I got my passport stamped saying that I applied and am waiting for that permit. While it is being processed, can I travel to other Schengen countries? My visa is still valid, but what about the 90/180 rule?


I am taking over a project from a previous developer and my client needs a way for email address to actually be a valid email address (ex: formatted as someone@something.com).   The form I'm working on is here:   All I am trying to do is validate this email via Ajax (what the old developer is using) before the form progresses.   Here is a snippet of JavaScript that is being used for validation right now:   // continue to next group     $('.iphorm .next').click(function() {         var error = false;         var checked = false;          // hide errors         $('.iphorm-errors-wrap').hide();         $('html, body').animate({scrollTop:$('.page_content').position().top}, 100);          // validate text inputs         $(this).parents('.iphorm-group-wrap').find('.iphorm-element-wrap-text.iphorm-element-required input').each(function() {              if ($(this).is(':visible')) {                 if ($(this).val() === '') {                     $(this).parents().next('.iphorm-errors-wrap').show().html('

This field is required

');                       error = true;                 }             }         });     });   Does anyone have any idea of how I could accomplish some simple email validation before the form moves on to the second step?

Is there a regular expression to validate an email address in JavaScript?


Suppose we have $X_i \stackrel{\text{i.i.d}}{\sim} U(0,1)$ and we define a stopping time $N =\min \{n \mid X_1+\dots +X_n >1\}.$ How can one find the distribution of $X_N$?  I have seen how to find the distribution of $N$ using the renewal function $m(t)$ (in particular, $E[N]=e$) but I cannot figure out how to see the distribution of $X_N$. Through bootstrap methods, I see it is not just uniform, but I don't see why.

Let $X_1,X_2,X_3,\ldots $ be an i.i.d. sequence of uniform random variables over $[0,1]$. Define $$N= \min \{n \geq 1:X_1+\cdots+X_n>1\}$$ Find $P\{N>n\}$ and compute $E[N]$.


I was thinking what if my AWS Account gets deleted or is inaccessible one day? Has anyone implemented a solution for this? Can we backup from one AWS account and restore to another AWS account?  Currently am using Skeddly to backup my AWS instances, which is again stored in AWS itself.  Any thoughts?

We've centered most of our operations on AWS, and love the ease of use there. However, every once in a while, the paranoid side of my brain wonders ?  Within the Amazon ecosystem, we have a pretty good backup plan: We keep most static data in S3. EBS volumes are snapshotted nightly. However, true paranoia would mean backing up to a provider outside the Amazon ecosystem. How do you handle doing this? I'm especially interested in backing up EBS snapshots and S3 contents. Bonus points for backing up RDS.


is a Nikon d700 with sc < 5k for 950SGD a good buy? What are the things that I should take note of before buying? Please suggest. Thanks.

I'm considering buying a DSLR from a friend. I've read the  question elsewhere on this site, but I was wondering what I should look at on the body to assess the condition?


In the following document, the two paragraphs should be composed in the same way. But the spacing before 'high punctuation' characters (;) is not correct in the paragraph created by the \lipsum macro.  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{lmodern} \usepackage[french]{babel}  \usepackage{filecontents} \begin{filecontents}{lipsum-babel-test.ltd.tex} \ProvidesFile{test.ltd.tex}  \NewLipsumPar{Pour moi, je n'ai jamais présumé que mon esprit fût en   rien plus parfait que ceux du commun; même j'ai souvent souhaité   d'avoir la pensée aussi prompte, ou l'imagination aussi nette et   distincte ou la mémoire aussi ample ou aussi présente, que quelques   autres. Et je ne sache point de qualités que celles-ci qui servent à   la perfection de l'esprit; car pour la raison, ou le sens, d'autant   qu'elle est la seule chose qui nous rend hommes et nous distingue des   bêtes, je veux croire qu'elle est tout entière en un chacun; et suivre   en ceci l'opinion commune des philosophes, qui disent qu'il n'y a du   plus et du moins qu'entre les accidents, et non point entre les formes   ou natures des individus d'une même espèce.} \end{filecontents}  \usepackage{lipsum} \SetLipsumText{lipsum-babel-test}  \begin{document}  \lipsum[1]  Pour moi, je n'ai jamais présumé que mon esprit fût en rien plus parfait que ceux du commun; même j'ai souvent souhaité d'avoir la pensée aussi prompte, ou l'imagination aussi nette et distincte ou la mémoire aussi ample ou aussi présente, que quelques autres. Et je ne sache point de qualités que celles-ci qui servent à la perfection de l'esprit; car pour la raison, ou le sens, d'autant qu'elle est la seule chose qui nous rend hommes et nous distingue des bêtes, je veux croire qu'elle est tout entière en un chacun; et suivre en ceci l'opinion commune des philosophes, qui disent qu'il n'y a du plus et du moins qu'entre les accidents, et non point entre les formes ou natures des individus d'une même espèce. \end{document}   Result:    Where is the problem and how to fix it?

I am preparing a document in French, using the "babel" package with option "french" and using commands that include colons and semicolons. My problem is, the French spacing before colons and semicolons disappears when the commands are printed. I do not understand why, have not been able to find an answer. Below is a MWE.  \documentclass{article} \usepackage[french]{babel} \newcommand\deuxpoints{Texte: texte} \begin{document} \deuxpoints\ \endgraf Texte: texte \end{document}


I have to install Ubuntu alongside windows 10 (UEFI boot) on a brand new Dell XPS 13.   I already have:   Shrinked the Windows 10 disk to have 200Gb unused space Disabled Secure boot Created the USB boot loader, and boot with it   The problem, is that, when the installer starts, it doesn't see the laptop disk, so I cannot go on with the install

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?


Let $R$ be a relation on two countable sets $A$ and $B$, where $R\subset A\times B$, with the following properties:   $\forall a\in A$ the set $\{b\in B: (a,b)\in R\}$ is finite. For any finite set $A_0\subset A$: $$|\{b\in B : \exists a_0\in A_0, \text{such that} \ \ (a_0,b)\in R  \}|\leq n|A_0|$$ where $n\in\mathbb{N}$.   I need to show then, that there exist $n$ disjoint sets, $B_1,B_2,\dots, B_n$, where $B_i\subset B\ \ \ \ \ \ \forall \  \ 1 \leq i\leq n$, and there exists $n$ one to one and onto functions $f_1,f_2,\dots, f_n$ such that $f_i:B_i\to A \ \ \ \ \ \ \ \forall \  \ 1 \leq i\leq n $?  Thank you for your help.

Let $R$ be a relation on two countable sets $A$ and $B$, where $R\subset A\times B$, with the following properties:   $\forall a\in A$ the set $\{b\in B: (a,b)\in R\}$ is finite. For any finite set $A_0$: $$|\{b\in B : \exists a_0\in A_0, \text{such that} \ \ (a_0,b)\in R  \}|\leq n|A_0|$$ where $n\in\mathbb{N}$.   How can I show then, that there exist $n$ disjoint sets, $B_1,B_2,\dots, B_n$, where $B_i\subset B\ \ \ \ \ \ \forall \  \ 1 \leq i\leq n$, and there exists $n$ one to one and onto functions $f_1,f_2,\dots, f_n$ such that $f_i:B_i\to A \ \ \ \ \ \ \ \forall \  \ 1 \leq i\leq n $?  Edited:  $B_i\in B$ replaced with $B_i\subset B$


I have been trying to figure out the following limit: $$\lim_{n\to\infty} \sqrt[n(n+1)]{\prod_{r=0}^n {n\choose r}}=\mathscr L$$ It’s quite natural to take the natural log of both sides: $$\ln \mathscr L = \lim_{n\to\infty} \frac{\sum_{r=0}^n \ln {n\choose r}}{n(n+1)} \\ =\lim_{n\to\infty} \frac{(n+1)\ln(n!) - 2\sum_{r=0}^n \ln(r!)}{n(n+1)}\\  =\lim_{n\to\infty} \frac{(n+1)\ln(n!) - 2\ln(\color{green}{n! \times (n-1)! \times (n-2)! \dots \times 2!\times 1!})}{n(n+1)}$$ I believe the green term is called the superfactorial of $n$, but I barely know anything about it. The last thing I tried was to write $$n! \times (n-1)! \times (n-2)! \dots 2!\times 1! =n^1 \times (n-1)^2 \times (n-2)^3 \dots \times 2^{n-1} \times 1^n = \prod_{r=1}^n r^{n+1-r}$$ but that doesn’t help. Any ideas on how to evaluate this limit?

I am facing difficulty with the following limit. $$ \lim_{n\to\infty}\left(\binom{n}{0}\binom{n}{1}\dots\binom{n}{n}\right)^{\frac{1}{n(n+1)}} $$ I tried to take log both sides but I could not simplify the resulting expression. Please help in this regard. Thanks.


The question asks to prove that if  "$x_1,x_2,x_3$ are positive numbers show that: $$(x_1+x_2+x_3) \left(\frac{1}{x_1}+\frac{1}{x_2}+\frac{1}{x_3} \right)\ge 9$$  I've tried to use the fact that the arithmetic mean is greater than the harmonic mean since it looks like it's kind of in that form but it doesn't seem to work. I tried expanding it too and simplifying a little to get: $$ x_1^2(x_2+x_3)+x_2^2(x_1+x_3)+x_3^2(x_1+x_2)\ge 6 x_1x_2x_3$$  but I can't seem to see anyway to further get it into a form that easily proves the required inequality. Any hints as to a way to do this?

Given that $a,b,c$ are distinct positive real numbers, prove that $(a + b +c)\big( \frac1{a}+ \frac1{b} + \frac1{c}\big)>9$   This is how I tried doing it:  Let $p= a + b + c,$ and $q=\frac1{a}+ \frac1{b} + \frac1{c}$.  Using AM>GM for $p, q$, I get:  $$\frac{p+q}{2} > {(pq)}^{1/2}$$ $$\sqrt{(a + b +c)\bigg(\frac1{a}+ \frac1{b} + \frac1{c}\bigg)} < \frac{\big(a+\frac1{a} + b+\frac1{b} + c+\frac1{c}\big)}2$$ And for any $x\in \mathbb{R}, \space \space x+\frac1{x}≥2.$ Thus,   $$(a + b +c)\bigg(\frac1{a}+ \frac1{b} + \frac1{c}\bigg)<9, $$ which is the opposite of what had to be proven. What did I do wrong?


It's very un-certain in S04E12 (End Time) who poisoned Brock. Was it Walt or Gus who poisoned him? How was he even poisoned?   If Gus poisoned Brock then he'd get Jesse to kill Walt. If Walt poisoned Brock then he'd get Jesse to turn against Gus.

I've seen Breaking Bad complete series 2-3 times, but I never found out how Walter White was able to poison Brock.  I mean did he himself directly feed the Valley of the Lilly berries to Brock or did he let Saul do the work? I can't figure it out.


Is there a native app for Stack Overflow for iPad/iOS?  The site's not too bad on iPad via the browser, but it's also a bit of a pain to use at times.

I like using Stack Overflow (or any other Stack Exchange sites) and was wondering if there was an app I could install on my phone or other device that would allow me to use the site on-the-go or straight from my desktop.  Some systems to consider:   Windows 8 Android iPhone/iOS   What are some apps that I could install to my computer or phone to enhance my Stack Exchange experience?


The surface tension of water reduces on addition of soap to it. Then why does normal water not form bubbles but soap does even with less surface tension?

Why are soap bubbles made of soap? What I know is  to have stability in bubble, waterproofing agents should me mixed, but soaps are water wetting agents, and water wetting agents will decrease angle of contact.   Can someone correct me?


I am getting the following error message...  "The application “Blender” can’t be opened."  No follow up information, no "...because we can't identify the developer, etc.," just that.  Please help!

I downloaded Blender onto my Mac laptop, but it will not open. When I try to open it, I get an error message that says, "'Blender' can't be opened because it is from an unidentified developer." I'm not sure what to do to get it to open. :/


The last week of next month ubuntu will most likely release 18.04 LTS. Now my system is 14.04 and next month I want to upgrade it to 18.04. Can I directly upgrade my system from 14.04 to 18.04 or I have to first upgrade from 14.04 to 16.04 and then to 18.04? I really want to avoid the second method of upgrading.  Edit:  How should I update 14.04 to 16.04. I tried this method sudo update-manager -d and installed all the necessary software and restarted the system. Again I run sudo update-manager -d and it showed that my computer is upto date but doesnt have any button to update to 16.04

What are the different ways I can use to upgrade Ubuntu from one release to another?