I faced a weird linking problem when trying to compile my source code. I paste my code below for better explanation.  LinkedList.h  #ifndef _LINKED_LIST #define _LINKED_LIST  #include <iostream> #include "ListInterface.h" #include "Node.h" #include "PrecondViolatedExcep.h"  template<class ItemType> class LinkedList : public ListInterface<ItemType>{............ //There is the some code here, but thats not the point so i don't  #include "LinkedList.cpp" #endif   main.cpp  #include "LinkedList.h"  int main() {     LinkedList<int> list; }   You can see that under the LinkedList.h header file, i included this line #include "LinkedList.cpp at the bottom.  So now i can compile like this: g++ main.cpp -o main. This give me no problem at all the program works correctly.  But the linking problem appear when i remove this line #include "LinkedList.cpp at the bottom of LinkedList.h header file. And i compile like this: g++ main.cpp LinkedList.cpp -o main. Theoretically this should not be a problem, i done this most of the time with other projects. So this problem is kind weird for me. Can anyone pointing out what is the cause of this?

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


Does anyone know how one can recover your Gmail account which has two factor authentication enabled when:   you lose the printed codes and your authorized phone + laptop are unavailable?   I lost my laptop bag (cellphone + laptop + wallet) and have two factor authentication enabled - and for better or worse (worse right now!) I had decided to assign my Google account as the center of my digital identity.   Is there a phone number I can call them up on or any other setting / configuration?

I have forgotten the password or username for my Google account, or I'm unable to access my account for other reasons.  How can I recover my account?  (This Q&A is meant as a general description for all Google and Gmail username/password questions. See: )


I am trying to replace a word in a text file with the current username. I am trying to do this with "sed" using $USER, but it keeps actually writing "$USER" in the text file instead of my username.  sed -i 's/test/$USER/g' ~/.gtkrc-2.0   Can anyone help? Thank you in advance.

I tried the following code to replace QQ with ZZ, but it doesn't do what I want:  var1=QQ sed -i 's/$var1/ZZ/g' $file   However, this code does what I want:  sed -i 's/QQ/ZZ/g' $file   How do I use variables in sed?


I am using ajax cart on a shopify theme and I have added a countdown timer on the cart drawer. I want the count timer to clear when there are no items left in the cart, the only way I have been able to do that is if I reload the page. How can I achieve the result of once the cart dawer is empty the countdown clears without needing to reload the page? The below code doesn't seem to work.   setInterval(function () {     var cartContents = fetch('/cart.js')     .then(response => response.json())     .then(data => {       if (data.item_count == 0){               sessionStorage.removeItem('count');       }             console.log(data.item_count);     });   }, 1000);

I am using setInterval(fname, 10000); to call a function every 10 seconds in JavaScript. Is it possible to stop calling it on some event?   I want the user to be able to stop the repeated refresh of data.


Is there a shortcut for adding a using directive without having to leave the point where I'm working in the code to scroll up to the top of the file?  For instance, if I don't have using System.IO; and I add string fullPath = System.IO.Path.Combine(path1, path2); to a method where I'm working, I'd like to be able to right-click or something to get the option to add using System.IO; at the top and remove it from the beginning of System.IO.Path.Combine.  I'm know third-party tools like Re-Sharper can enable this, but I thought this would be a simple feature that would be present by VS 2017.

What is the keyboard shortcut to expand the little red line that gives you the menu where you can choose to have the necessary using statement added to the top of the file?


I want to know a word or a phrase that would describe a person who "intentionally" (because some people hate themselves even when they don't want to, or some people are insecure - making some generalizations, forgive me if I miss out something.) insults themselves to make others try to make them feel better by complimenting them. Here is an example of a conversation :  A: Hello B, how is it going?  B: Nice. I just wish my purple dress didn't make me look even uglier.  A: That isn't the case babe, I think you are amazing. You are really soo beautiful.  B: NO I am HIDEOUS, and I know it, don't lie to me.  A: No, I promise. I won't lie you're my BFF. You Rock girl.

I'm wondering about this in relation to the notion of a "culture of victimization", when people want to garner sympathy and/or discharge their guilt by being considered victims.  The phrase "culture of victimization" refers to the situation of many people having that desire and not to the desire itself. "Masochism" is close I suppose, but somehow not quite right.


In A.h:  namespace ns {     template <typename T>     class A {     public:         static void test();     } }   In A.cpp:  #include "A.h"  using ns::A;  template <typename T> void A<T>::test() {     // Do something }   In main.cpp:  #include "A.h"  using ns::A;  int main() {     A<int>::test();     return 0; }   The compiler says:  main.cpp:(.text+0x5): undefined reference to `ns::A<\int>::test()'  collect2: error: ld returned 1 exit status


HTML <select style="margin-left: 10px;" id="myDropDown">         <option value='' disabled selected>Assign Table</option>         <option value='1'>Table1</option>         <option value='2'>Table2</option>         <option value='3'>Table3</option>     </select>

         <input type="text" id="total" value="0" readonly="readonly" />  Javascript $('#myDropDown').change(function() {         //Selected table         var inputValue = $(this).val();         var HTML;         var HTML2;         if (inputValue == 1) {         HTML = '
<input id="test-element" type="checkbox" price="1">price 1

<input id="test-element" type="checkbox" price="2">price 2
';        }        else if(inputValue == 2) {        HTML = '
<input id="test-element" type="checkbox" price="3">price 3

<input id="test-element" type="checkbox" price="4">price 4
';       }       document.getElementById('myTable').innerHTML = HTML;    });          function calcAndShowTotal(){     var total = 0;     $('#myTable :checkbox[checked]').each(function(){         total += parseFloat($(this).attr('price')) || 0;         alert("working");     });     $('#total').val(total);    }  $(document).on("click",'#myTable :checkbox',function() {       //alert("working");     calcAndShowTotal(); });  calcAndShowTotal();  I made a dropdown that toggles between different checkboxes with .innerHTML. I updated the click function to be $(document).on and it works on every click but the total value doesn't change. Why doesn't calcAndShowTotal function work? I tried changing it to $(document).on too but it doesn't calculate total. Check fiddle link for example.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I'm just trying to scale down an iframe:   <iframe src="http://www.swpc.noaa.gov/rt_plots/kp_3d.html" scrolling="no"  width="600" height="500"             style="padding: 0px; margin: 0px; zoom: 0.25; -moz-transform: scale(0.25); -moz-transform-origin: 0 0; -o-transform: scale(0.25); -o-transform-origin: 0 0; -webkit-transform: scale(0.25); -webkit-transform-origin: 0 0;"> </iframe>right content<br>bottom content   Scaling itself works fine but my problem is that after scaling the iframe still requires the original space. Setting margin and padding to 0 did not help. Firebug selects the scaled area only when I hover the iframe element. How can I remove the space at the right and at the bottom? What I really want to is to keep the original size but only scale down the content so that it still fills the space. But obviously it's not possible to access the CSS of the iframe's content. Any advice is appreciated. Best regards - Ulrich

How can I scale the content of an iframe (in my example it is an HTML page, and is not a popup) in a page of my web site?  For example, I want to display the content that appears in the iframe at 80% of the original size.


I have a question regarding Linux and Unix non-user service accounts. We know there are user accounts in Linux , what are (non-user) service accounts such as daemon,news, bin, etc used for?  $cat /etc/passwd | more    reveals all the user and non-user accounts.  Why has bin has been assigned service account? Is this by design, or it serves a special purpose?  Last question  Is this true in Microsoft operating system environment( Server 2003, or 2008).?

Some  I'm going through has a boolean switch on whether or not a user is a 'system' user or a 'normal' user (defaulting to 'normal').  What is the difference between these two modes of user-ship?  I don't need to learn what a user is or why you need them (even 'fake' ones), but this particular distinction isn't intuitive to me.


How do I get a sword with sharp 1000 on Java? My friend is on bedrock and he has a sharp 100 sworrd. I tried it but didn't work. I wanted to know how to get it to work on 1.16.5. The tutorial is on 1.12.2 so how do I do it with commands?

I'm making a map where I want players to be able to choose there kits/classes. The problem I'm having with it though is giving players already enchanted Tools/Armour/Weapons.  I'm not sure if you can use the /give [player] [item] [amount] because you'll have to use the whole {} thing and I'm not sure how to make enchanted Tools/Armour/Weapons using that.  Can anyone help?


how many months is it when somebody says:     Expats should take note that the hurricane season runs from June to   November, and extreme weather can be a safety issue.   Does it mean that the season runs for 6 or 5 months?  E.g. does it mean that the Hurricane season ends in November or after november - meaning it ends in December?  If I said:     Expats should take note that the hurricane season last from June until   November, and extreme weather can be a safety issue.   Does it now mean that it lats only 5 months? That starting November the season is over?  Thank you for explaining!

What is the difference between " from ～to～" and "from ～ through～"? For example,  are the following sentences same?  I work from Monday to Friday. I work from Monday through Friday.


When I read the new Star Trek comics (for the Kelvin timeline) I wondered only one thing: How canon are they? (in regards to the film-series)

Star Wars has different levels of canon and explanations for each level (movies, books, games and so on).  From what I've seen in Star Trek, there seems to be one level of canon: If it was on screen (other than the animated series), it's canon (although some people claim the 2009 movie and Star Trek: The Final Frontier don't really count).  If it's not on screen, it's not canon.  Is that it?  Or are there some games that are a second level of canon, or some books or other material considered to be a higher level than other media?  Or is there just one level of canon in Star Trek?


what does it mean  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


I have this  in spherical coordinates taken from . I would like to use this figure to illustrate unit vectors at the point P. I have not been able to adapt the figures given on various posts. I manged to run the asymptote code  but in pdf format it comes compressed such that it is unreadable. I would appreciate if someone can add me some code in tikz so that I can draw a circle through P, with vectors in the three directions, east, north and zenith. I reproduce the code from the first site quoted above (appreciation and thanks @jubobs)  Yes the code by jubobs is half of what I want. What I want added to this are three unit vectors in the direction of the coordinate direction, i.e. at P we probably would have a circle running from north pole to south pole, and through P a vector in z-direction, a vector in $\phi$ direction and a vector in $\theta$ direction.  Please note that I am only adding a small addition to this post. The addition is explained in the last paragraph above.  The code supplied by mammot does exactly what I was looking for, my real appreciation for spending time and effort mammot. When I incorporate the code I get . I had tried to turn the vector in the positive x-direction (opposite to what is the figure) no success so far. Seconddly I would appreciate adding a circle from north pole to south pole through P. Sorry for being too demanding, but the work is done. This is what I wanted and its fine. Once more my appreciation.  \documentclass{article}  \usepackage{tikz} \usepackage{tikz-3dplot}  \begin{document} \tdplotsetmaincoords{60}{110} \pgfmathsetmacro{\rvec}{.8} \pgfmathsetmacro{\thetavec}{30} \pgfmathsetmacro{\phivec}{60} %  \begin{tikzpicture}[scale=5,tdplot_main_coords] \coordinate (O) at (0,0,0); \draw[thick,->] (0,0,0) -- (1,0,0) node[anchor=north east]{$x$}; \draw[thick,->] (0,0,0) -- (0,1,0) node[anchor=north west]{$y$}; \draw[thick,->] (0,0,0) -- (0,0,1) node[anchor=south]{$z$}; \tdplotsetcoord{P}{\rvec}{\thetavec}{\phivec} \draw[-stealth,color=red] (O) -- (P) node[above right] {$P$};  \draw[dashed, color=red] (P) -- (Pxy); \tdplotdrawarc{(O)}{0.2}{0}{\phivec}{anchor=north}{$\phi$} \tdplotsetthetaplanecoords{\phivec} \tdplotdrawarc[tdplot_rotated_coords]{(0,0,0)}{0.5}{0}% {\thetavec}{anchor=south west}{$\theta$} % \tdplotsetthetaplanecoords{\phivec} \tdplotdrawarc[tdplot_rotated_coords]{(0,0,0)}{0.5}{0} {\thetavec} {anchor=south west}{$\theta$} \coordinate (Shift) at (P); \tdplotsetrotatedcoords{-\phivec}{-\thetavec}{\phivec}; \tdplotsetrotatedcoordsorigin{(Shift)}; \begin{scope}[tdplot_rotated_coords,scale=0.4,blue] \draw[thick,->] (0,0,0) -- (1,0,0) node[anchor=north east]{$x'$}; \draw[thick,->] (0,0,0) -- (0,1,0) node[anchor=north west]{$y'$}; \draw[thick,->] (0,0,0) -- (0,0,1) node[anchor=south]{$z'$}; \end{scope} \end{tikzpicture} \end{document}

For some lecture script I am preparing I would need some descriptive images showing how to work with spherical coordinates as often seen in textbooks, i.e. a globe and some descriptive arrows annotating \Phi, \Theta, etc.  Can someone tell me if, and how, this can be done in latex (I am a fairly familiar with LaTeX for typesetting text but a novice when it comes to PSTricks and co.)!


I would like to copy for backup porposes a Linux user home directory with several GBs of data and the usual configuration files. The source directory and the backup directory should exactly have the same contents. The OS is Lubuntu.  The directory contains hidden files and subdirectories. After some googling I found that  cp -r /source-directory /backup-directory   was the appropriate command.  The source directory filesystem is ext4 and the destination directory is NTFS. After the copy, diff -qr /source-directory /backup-directory gives no output (so I suppose no differences). But du, or du -b or du --apparent-size all give always different outputs for the source directory and the backup directory.  Why? Was the command wrong or is this use of du wrong?

I am a graduate student of computational chemistry with access to a Linux cluster.  The cluster consists of a very large (25 TB) fileserver, to which several dozen compute nodes are connected.  Each compute node consists of 8 to 24 Intel Xeon cores.  Each compute node also contains a local disk of about 365 TB.  Since the fileserver is routinely accessed by a dozen or so users in the research group, the fileserver is mainly used for long term file storage (it is backed up nightly, whereas the compute nodes' local disks are never backed up).  Thus, the system administrator has instructed us to run simulations on the local disks -- which have faster I/O than the fileserver -- so as to not slow down the fileserver for the other users.  So, I run simulations on the local disks and then, after they are finished, I copy the trajectory files -- I am running molecular dynamics (MD) simulations -- to the fileserver for storage.  Suppose I have a trajectory file called traj.trr in a directory on the local disk of a node, /home/myusername/mysimulation1/traj.trr.  For long term storage, I always copy traj.trr to a directory in the fileserver, ~/mysimulation1/traj.trr, where ~ represents my directory in the fileserver, /export/home/myusername.  After copying it, then I habitually use du -h to verify that /home/myusername/mysimulation1/traj.trr has the same file size as ~/mysimulation1/traj.trr.  This way, I can be at least reasonably sure that the transfer to the fileserver was successful.  For example:  cd /home/myusername/mysimulation1/ cp -v traj.trr ~/mysimulation1/ du /home/myusername/mysimulation1/traj.trr -h du ~/mysimulation1/traj.trr -h   If the two calls to du -h give the same human-readable file size, then I can be reasonably sure that the transfer/copy was successful.  (My typical traj.trr files range in size from about 15 to 20 GB, depending on the exact simulation I have run.)  If I run du (i.e., without the -h switch) on the two traj.trr files, their sizes in bytes are usually very, very similar -- usually within just a few bytes.  I have been using this overall method for the past year and a half, with no problems.   However, recently I have run into the following problem: sometimes du -h reports that the two traj.trr files are different in size by several GB.  Here is an example:  cd /home/myusername/mysimulation1/            # this is the local disk cp -v traj.trr ~/mysimulation1/ du traj.trr -h cd ~/mysimulation1/                           # this is the fileserver du traj.trr -h   The output from the two calls to du -h is as follows, respectively:  20G     traj.trr 28G     traj.trr   I believe that the former (i.e., the traj.trr in the local disk, /home/myusername/mysimulation1/) is the correct file size, since my simulation trajectories are expected to be about 15 to 20 GB each.  But then how could the file on the fileserver actually be larger?  I could see how it could be smaller, if somehow the cp transfer failed.  But I don't see how it could actually be larger.    I get similar output when I execute the same commands as above, but without the -h switch given to du:  20717480        traj.trr 28666688        traj.trr   Can you think of any reason for the difference?    If, by some unlikely chance, du is somehow malfunctioning, I can be okay with that.  But I just really need to make sure that the copy of traj.trr on the fileserver is complete and identical to its source version on the local disk.  I need to delete the local file so that I have enough local disk space to run new simulations, but I can't afford to have the version of traj.trr on the fileserver be corrupted.    The  is a binary format, not text.  Thus, I am not sure if the files can be reliably compared by a program such as diff.


I want to give the value of 0 in this raster but only in the area within the polygon. So the final outcome is the same raster file but with 0 values in that area How can I do that?

How do I change the values of raster cells which are within a polygon, leaving all cell values outside the polygon unchanged? I would like to subtract 1.5m from each raster cell value within the polygon, rather than make them all the same value. I don't know how to use GRASS so I'm hoping there is a way to do it using the tools within the QGIS GUI, raster calculator, or processing toolbox. I'm using QGIS 2.0.


In a flat space, where special relativity works, a travelling body can only return to the same point if we apply some kind of acceleration to the body.  So twin paradox is not a paradox because a travelling body that returns to the same point where it starts is not an inertial reference.  But then we have general relativity, that states that mass (energy) curves space-time. So when a photon changes its trajectory passing nearby sun, it's actually moving in a straight line, but in a curved space-time.  Now we can create a new version of twin paradox, where the spaceship that carries one of the twins uses the curvature of some astronomical body (like Jupiter, sun or a black hole) to return to the same point?  In that case which twin will be older?  How to solve the paradox in this context?

Take the following gedankenexperiment in which two astronauts meet each other again and again in a perfectly symmetrical setting - a hyperspherical (3-manifold) universe in which the 3 dimensions are curved into the 4. dimension so that they can travel without acceleration in straight opposite directions and yet meet each other time after time.  On the one hand this situation is perfectly symmetrical - even in terms of homotopy and winding number. On the other hand the Lorentz invariance should break down according to , so that one frame is preferred - but which one?  So the question is: Who will be older? And why?  And even if there is one prefered inertial frame - the frame of the other astronaut should be identical with respect to all relevant parameters so that both get older at the same rate. Which again seems to be a violation of SRT in which the other twin seems to be getting older faster/slower...  How should one find out what the preferred frame is when everything is symmetrical - even in terms of GRT?  And if we are back to a situation with a preferred frame: what is the difference to the classical Galilean transform? Don't we get all the problems back that seemed to be solved by RT - e.g. the speed limit of light, because if there was a preferred frame you should be allowed to classically add velocities and therefore also get speeds bigger than c ?!? (I know  is only a local theory but I don't understand why the global preferred frame should not 'override' the local one).  Could anyone please enlighten me (please in a not too technical way because otherwise I wouldn't understand!)  EDIT Because there are still things that are unclear to me I posted a follow-up question:


I got a virus: now at least 30 Windows notifications a day show up, linking to spam websites. Windows Defender didn't find anything (wonderful). How can I find the location of the program triggering these notifications? I tried to right click on them but it does nothing.

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


I have a Micromax AQ4501 mobile phone. I am getting an exclamation mark over the Wi-Fi icon. And I am unable to connect to Wi-Fi thereafter.  I have been facing this problem since a few days after I upgraded my phone to Lollipop 5.0. I tried many things like:   switching off and then on,  replacing SIM from slot 1 to slot 2,  switching mobile data and Wi-Fi connection on and then off   but all in vain.   I called the Google call center but they were also unable to help me.   I am able to use internet through mobile internet, but unable to use Wi-Fi with this phone. My Wi-Fi is working fine on other gadgets like my laptop.   How can I resolve this problem?

When connected to the Internet, the system checks if it's in a walled garden, which is simply trying to connect to Google. If it fails, in Android 5, there'll be an exclamation mark on the WiFi icon or signal icon.   In some situations, this is annoying. Say, in China, Google is blocked, the exclamation mark will always be there, which is meaningless.  How can I disable this check, and make the system assume, connected WiFi/mobile data is connected Internet?


In taking apart my moribund wall thermostat I found a conductive rubber-ish connector between the PCB and LCD panel. It's cool stuff!  What's it called?

The LCD below is from a cheap digital clock which was (obviously) damaged (broken glass).    The electrical connection between the PCB and the display was realized with this pink strip.    Its flexible...    ...and consists of alternating rows of conductive and insulating material between the pink boarders.    [above image was altered in contrast/brightness to highlight the alternating strips]  What is this kind of connector called? Is it only used for displays?   I am pretty impressed that the connection is reliable just from the very slight pressure between the strip and the PCB. Also, its easily removable from the display. There seems to be some conductive layer on the glass, from where the signal goes into the displays internals. This connection seems to be damaged for the three rightmost signals, where the glass is broken.


Prove that if $w,z$ are complex numbers such that $|w|=|z|=1$ and $wz\ne -1$, then $\frac{w+z}{1+wz}$ is a real number.  Do I substitute $w$ and $z$ for $a+bi$ and $c+di?$ How do I do this?

This is my homework, which reads as follows: Let $z_1, z_2$ be complex numbers.  Prove that when $z_1z_2 \neq -1$ and $|z_1| = |z_2| = 1$, then the imaginary part of $$ \frac{z_1 + z_2}{1 + z_1z_2} $$ is zero.  I've tried to approach this in several ways, but whichever one I try, at some point the expression gets too large and doesn't simplify (at least I cannot find a way to simplify it).  The way I tried to approach this problem is to:   Set $z_1 = a+bi$, $z_2 = c+di$, then $z_1+z_2=(a+c)+(b+d)i$, and in polar form, $\sqrt{(a + c)^2 + (b + d)^2}\times (\cos\theta + i\sin\theta)$, $\tan \theta = \frac{b+d}{a+c}$. Find $\tan \phi$, where $\phi$ is the angle of $\frac{1}{1 + z_1z_2}$. Substitute into $\tan(\theta + \phi) = \frac{\tan(\theta)+\tan(\phi)}{1-\tan(\theta)\tan(\phi)} = 0$.   The problem is $\tan(\phi)$ is a huge expression, and I cannot get it to simplify, so I cannot also show that the last formula is actually true.  Since this is a homework, and we are expected to do this with pan and paper (not even a calculator...), I don't believe we are to do this many calculations by hand.  Hence, there must be some "trick" to get this to simplify, or a completely different approach.  Would you care to give me a hint?


I use the chocolate chip recipe on the bag but double the vanilla and add more chips than called for. I also add a bit more flour.   What I want to achieve is that old time chocolate chip cookie that is chewy flat and wide.  Can you offer a suggestion.  I still would use more chips and vanilla unless that might cause a problem. I am so glad I came apon your sight.

My chocolate chips cookies are always too crisp. How can I get chewy cookies, like those of Starbucks?    Thank you to everyone who has answered. So far the tip that had the biggest impact was to chill and rest the dough, however I also increased the brown sugar ratio and increased a bit the butter. Also adding maple syrup helped.


The force acting on a body of mass $m$ is $mg$, where $g$ is acceleration of free fall ! But why should there be a #uniform acceleration of free-fall in the first place? As per Newton's universal law of gravitation there's an inverse square law of force acting with respect to separation ; Thus as object falls towards Earth separation decreases and so the force, and hence acceleration, should likewise increase! How to reconcile this argument with a universally accepted constant acceleration $g$?

Newton's Law of Universal Gravitation tells us that the potential energy of object in a gravitational field is $$U ~=~ -\frac{GMm}{r}.\tag{1}$$  The experimentally verified near-Earth gravitational potential is  $$U ~=~ mgh.\tag{2}$$  The near-Earth potential should be an approximation for the general potential energy when $r\approx r_{\text{Earth}}$, but the problem I'm having is that they scale differently with distance.  $(1)$ scales as $\frac 1r$.  So the greater the distance from the Earth, the less potential energy an object should have.  But $(2)$ scales proportionally to distance.  So the greater the distance from the Earth, the more potential energy an object should have.  How is this reconcilable?


I'm not a technician and find most Ubuntu instructions are incomprehensible. I bought a printer for the first time in my life today, an HP 1515. I eliminated all Microsoft stuff from my computer last year. The HP installation disc seems incompatible with Ubuntu or with my Toshiba Satellite laptop. When I tried to understand the Ubuntu help page, I was invited to upgrade from Ubuntu 13.04 to 13.10. This in turn requires me to install something. I attempted to install Adobe Flash Player, but I couldn't. This also asks me to install updates to Ubuntu 13.04. This was also impossible to understand or to do.   Is there a simple way to make my printer work? I'd like to stick with free software, but I don't like these complications. I still haven't figured out how to double space, how to put numbers on pages, etc., and may be forced back to Microsoft if Ubuntu doesn't become user friendly for mere writers, not technicians. Thanks to all who offer suggestions.

Hplip is the software that drives most hp printers. Usually new printers are only supported in newer versions of the software. Canonical doesn't backport new versions packages to older Ubuntu versions, that means that newer drivers are not going to be available in the Software Center of older Ubuntu versions.  As an example yesterday I needed to hook a hp 1005p to a computer running 8.04. I was forced to install a newer hplip than the version available in the repositories. I installed it using the script from the hp page, but I'd like to know other alternatives.  Which is the best (technically, not the easiest) way to install it and why?.


I can generate the following but need to modify it to include shading of the intersection of circle A and B - C. Any suggestions? \documentclass[border=0.2cm]{standalone} % Required packages \usepackage[dvipsnames]{xcolor} \usepackage{tikz}   \begin{document} \begin{tikzpicture}[thick,     set/.style = {circle,         minimum size = 3cm,         fill=black!30}] % Set A \node[set,label={135:$A$}] (A) at (0,0) {};   % Set B \node[set,fill=white, label={45:$B$}] (B) at (1.8,0) {};   % Set C \node[set,label=$C$] (C) at (0.9,1.5) {};   % Intersection \begin{scope}      \clip (0,0) circle(1.5cm); \clip (1.8,0) circle(1.5cm); \clip (0.9,1.5) circle(1.5cm); \fill[white!60](1.8,0) circle(1.5cm);      \end{scope}  % Circles outline \draw (0,0) circle(1.5cm); \draw (1.8,0) circle(1.5cm); \draw (0.9,1.5) circle(1.5cm);   \end{tikzpicture}   \end{document}

I would like to delete, from the following figure:  the top circle, but without removing the black edge that separate the orange part from the gray part. The figure above has been obtained by the following code: \documentclass[border=0.2cm]{standalone}  % Required packages \usepackage[dvipsnames]{xcolor} \usepackage{tikz}   \begin{document} \begin{tikzpicture}[thick, set/.style = {circle,      minimum size = 3cm,      fill=black!30}]  % Set A \node[set,label={135:$A$}] (A) at (0,0) {};  % Set B \node[set,label={45:$B$}] (B) at (1.8,0) {};   % Intersection \begin{scope} \clip (0,0) circle(1.5cm); \clip (1.8,0) circle(1.5cm); \clip (0.9,1.5) circle(1.5cm); \fill[orange!60](0,0) circle(1.5cm); \end{scope}  % Circles outline \draw (0,0) circle(1.5cm); \draw (1.8,0) circle(1.5cm); \draw (0.9,1.5) circle(1.5cm);  \end{tikzpicture} \end{document}  A rough example of the desired result is:


$$           \int \frac { 1 } { 5 + 4 \cos x} \ dx $$  $$ \text{The solution given in the book for solving this was to use the identity.} $$   $$ \cos x = \frac{1 - \tan^2 \frac{x}{2}}{1+ \tan^2 \frac{x}{2}} $$  I was wondering if there was any other way for solving this  ?

I saw somewhere on Math Stack that there was a way of finding integrals in the form $$\int \frac{dx}{a+b \cos x}$$ without using Weierstrass substitution, which is the usual technique.   When $a,b=1$ we can just multiply the numerator and denominator by $1-\cos x$ and that solves the problem nicely.   But I remember that the technique I saw was a nice way of evaluating these even when $a,b\neq 1$.


As the title suggests, I'm asked to describe the Galois group of the polynomial $x^4 - 5x^2 + 6 \in \mathbb{Q}[x]$ over $\mathbb{Q}$.  I am pretty certain I have 95% of the problem completed. I'm just having difficulty fully putting together the last step (I think it may boil down to a lack of knowledge in the "types" of groups).  The roots of this polynomial are $\pm \sqrt{2}$ and $\pm \sqrt{3}$. The automorphisms are thus: $$f_1(a + b\sqrt{2}) = a - b\sqrt{2} \\ f_2(a - b\sqrt{3}) = a - b\sqrt{3}$$  This resembles... something like... a group $\{e, \sigma_1, \sigma_2\}$ that has two coordinates? Something like $\sigma_1 \times \sigma_2$ where $\sigma_1$ cycles between itself and its negative and $\sigma_2$ cycles between itself and its negative.   I feel like there's just one little thing I'm missing.   (Edit: I think I've got it. This group is isomorphic to $\mathbb{Z}_2 \times \mathbb{Z}_2$, right?)

I want to compute the Galois group of some polynomials, but I want to see some examples first. For example this proposition could be helpful. I don't know how to prove it <.<  Let's consider a polynomial $f(x)= x^4+ax^2+b \in \mathbb{Z} $. Let $ \pm\alpha , \pm\beta$ denote the roots of $f(x)$. Note that $f$ is irreducible iff $\alpha^2, \alpha\pm\beta \notin \mathbb{Q}$. So let's suppose that $f(x)$ is irreducible. Let's denote $G$ the galois group of $f$ (the Galois group of the splitting field $\mathbb{Q}(\alpha,\beta)/\mathbb{Q}$)  $i)$ $G\cong V$ the Klein 4-group iff $\alpha\beta \in \mathbb{Q}$  $ii)$ $G\cong \mathbb{Z}_4$ iff $\mathbb{Q}(\alpha\beta)=\mathbb{Q}(\alpha^2)$  $iii)$ $G\cong D_8$ the dihedral group of order 8, iff $\alpha\beta \notin \mathbb{Q}(\alpha^2)$  I need help with the proofs of this propositions... Well I'm very lost with the computation of Galois group, some care must be exercised, I don't have it. For example I know that Galois group acts transitively, in the sense that $u\in K/F$ a galois extension, the other roots of the minimal polynomial of $m_u(x)\in F[x]$ are precisely the elements $ \sigma(u)$ , where $\sigma \in Gal(K/F)$. And clearly any automorphism, is determined by only the value of a basis. In this case we are working on $\mathbb{Q}(\alpha,\beta)$, so I have to know the values of both. But I have to respect the algebraic relations involving $\alpha , \beta$ I proved that in $i),ii)$ $\mathbb{Q}(\alpha,\beta) = \mathbb{Q}(\alpha) $ So I have to know the values on $\alpha$.   My first question is: If in both cases $i),ii)$, I have an extension of degree 4 (so $|G|=4$) I have to map $\alpha$ to determine the automorphism, but I have also to map $\alpha$ to all of it's four roots. Why the galois group in this case are different?  My second question is about $iii)$ I have no idea How to attack it.


I am writing a letter, with the following MWE (non-working, really):  \documentclass{scrlttr2} \usepackage{fontspec} \usepackage{marvosym} \usepackage[english]{babel}  \begin{document} \begin{letter}{x} \opening{} \end{letter} \end{document}   This code produces some lines in the margin to indicate where to fold or crease the letter (foldmarks).  (The x is added to avoid compiler errors.)  How do I get rid of them?

I need to create a letter using the scrlettr2 package. For this purpose, I wrote the LaTeX document given below.  But when I compile it I see marks on the side (see 3 red ellipses on the left).    How can I remove them?  Here's the source code:  % koma_env.tex \documentclass[a4paper,backaddress=off]{scrlttr2} % \usepackage{lmodern} \usepackage[utf8]{inputenc} % \usepackage[T1]{fontenc} % \usepackage[english]{babel} % \usepackage{url}    \setkomavar{fromname}{\{\{Landlord Name\}\}} \setkomavar{fromaddress}{\{\{Landlord Name\}\} \\ \{\{Landlord Correspondence Address Line 1\} \\ \{\{Landlord Correspondence Line 2 (if applicable)\}\} \\ \{\{Town/City\}\} \\ \{\{County\}\} \\ \{\{Postcode\}\}}  \begin{document}  \begin{letter}{\{\{Tenant Names\}\} \\ \{\{Property Address Line 1\}\} \\ \{\{Property Address Line 2 (if applicable)\}\} \\ \{\{Town/City\}\} \\ \{\{County\}\} \\ \{\{Postcode\}\}}  \KOMAoptions{fromphone=false,fromfax=false} \setkomavar{subject}{Pre Check-Out Inspection at \{\{1st line of Property\}\}}  \opening{Dear \{\{Tenant Names\}\}}  Your tenancy is due to come to an end on \{\{date\}\}. I would like to arrange an inspection at the property before the tenancy ends to identify anything that may lead me to retain some of your deposit if not addressed by the time I retake possession.  Carrying out this inspection prior to the tenancy ending will give you the opportunity to tackle anything raised and ensure I can return the maximum amount of deposit to you when the tenancy ends  I would like to carry out the inspection on \{\{date\}\} at \{\{time\}\}. It would be best if you were present then if anything is identified we can discuss this and be clear on what would be required to rectify it. Please can you contact me as soon as possible to confirm whether or not this is convenient.  If you do not wish to be present I have a set of keys to access the property and will send you the results of the inspection. Please let me know either way at your earliest convenience.  \closing{Kind Regards}  \end{letter}  \end{document}


I am trying to get a Schengen visa for my trip to Italy in September at the Italian Consulate in Miami. Unfortunately, there are no appointments for next three months!   Is there any hope at all of getting a visa in this time frame? I still have nearly 7 weeks before my trip, but we are already talking about cancellations etc., because of no visa appointments. Any strategies that would work?  There is a waiting list for the Italian Consulate Miami, but I am not sure how reliable it is going to be.

I am planning on traveling to Europe in two months. However, I could not find any appointments for Schengen C visa for the next two and a half months.  Is there any way around this? What's the probability of me getting this visa? It would be a shame if I have to call off my vacation because of visa appointments not being available, or if I have to change my itinerary to include a country where there is a visa slot.


I know that if a subgroup A is normal subgroup of the subgroup B,then B is contained in the normalizer of A . But I don not know what is the meaning of A normalizes B ?

Let $A$ and $B$ be two subgroups of the same group $G$. What does it mean for the subgroup $A$ to be normalized by the subgroup $B$?


should they be in italics like books and newspapers? I know about the latter but what about foreign magazines?

In which cases is a word, or a group of words written in italics? Is italics used in specific contexts, or it is quite normal to write words in italics?


When viewing the revision history of very long posts, only the changed parts of the posts are shown, while the rest is hidden. For example, in the revision history of , we see the following:  Inside the red freehand "circle", we see two links: one link with text "link" that generates a link to this revision, and one link with text "full" that shows the full diff, and not only the changed parts. However, these links are so close together that they seem to be a single link with text "link full", which would seem to mean "get a link to the full version of this revision" or something like that. This seems to happen only for very long posts, and seems to be network-wide (see an example on Spanish Language Meta ). Can this be fixed?

When looking at , there is very little space between link and full:    Info:   iOS 13.4.1 Firefox 25.1


This is possibly a duplicate, but I was unable to find a post that would answer this question. If you do find it, please put it in comments and I will delete my post.  Suppose you have a $\{0,1\}^X$ which is the set of mappings from $X$ to $\{0,1\}$, show that there exists a bijection from $\{0,1\}^X$ to $\mathcal{P}(X)$.  I know that $X$ cannot be finite, but to understand better the situation, I first assumed $X$ to be finite. Then by using combinatorics notions, I could see that $\{0,1\}^X$ most likely would have $2^{|X|}$ elements, just like $\mathcal{P}(X)$. Yet in case $X$ is infinite(and it always is), $2$ to the power of infinity doesn't make much sense. Could you show me how to show that there exists a bijection? Or is there a theorem for that?

Given any set $X$, let $P(X)$ be the set of all subsets of $X$, and let $\{0,1\}^X$ be the set of all functions $X \rightarrow \{0,1\}$. Construct a bijection (and its inverse) between P(X) and $\{0,1\}^X$.    Let us define $f: P(X) \rightarrow \{0,1\}^X$ by $f(\alpha) = g_{\alpha}$ where $\alpha \in P(X)$ and $g_{\alpha} : X \rightarrow \{0,1\}$ is defined by  $$g_{\alpha}(x) =\begin{cases}        1 & x \in \alpha \\       0 & x \in X-\alpha     \end{cases}$$  We need to check if this function is well-defined. Let $\alpha, \beta \in P(X)$. If $\alpha=\beta$, then $\alpha$ and $\beta$ correspond to the same set, and so correspond to the same function since both $g_{\alpha}$ and $g_{\beta}$ send that set to 1 and the ($X-$that set) to 0.   If we have a function $g_{\alpha} \in \{0,1\}$, then $\alpha$ is a set in $X$ that is sent to 1. But since $P(X)$ is the set of all sets of $X$, we must have $\alpha \in P(X)$. So the function is surjective.  Finally, if $g_{\alpha}=g_{\beta}$ then both $g_{\alpha}$ and $g_{\beta}$ send the set $\alpha$ or $\beta$ to 1. So $\alpha$ and $\beta$ must be same set. In other words, the function is injective; and hence bijective.   The inverse function is $f^{-1}: \{0,1\}^X \rightarrow P(X)$ where $f^{-1}(g_{\alpha}) = \alpha$.     Another way to prove this is to first construct the inverse function, show that it is well defined, and then show that $ff^{-1}$ and $f^{-1}f$ are the identity functions, right?  So if we let $g_{\alpha}=g_{\beta}$, then $\alpha=\beta$, because otherwise $g_{\alpha} (\beta)=0$ and $g_{\beta} (\beta)=1$; a contradiction.   Now we have $f \circ f^{-1} (g_{\alpha}) = f(\alpha) = g_{\alpha}$ and $f^{-1} \circ f(\alpha) = f^{-1}(g_{\alpha}) = \alpha$ , and so $f$ and $f^{-1}$ must be bijective.


After updating my nexus 4 to new android 5 (lollipop) when i open an apk file, the install button not working!! Also i checked unknown source in my device settings.    What the problem? please help :(

I'm trying to sideload an application, as seen in the picture below.    I have allowed the installation of applications from unknown applied actions in settings, but I can't seem to press the install button. The cancel button works correctly and installing applications via adb install works correctly. What's the problem?  EDIT: For those who have this problem, using ChainFire's  will correct it because the app uses hardware compositing, and Android doesn't notice a "layer" on top of the current screen.


Can anyone suggest a free face matching app for use on a Windows 10 computer? I have a photo of my grandmother at the age of 20 and another photo that may be her at the age of perhaps 50. Alternatively, it may be her mother. What would be ideal would be to be given a percentage likelihood that this was either the same person or probably closely related.

A cousin of mine was doing some Thorp research, and found several unidentified photos that were in an album with some  photos and was wondering if there is a good facial recognition software that may be helpful in identifying the men in the photos?  In other words, could we teach such software with identified photos of men of various ages that are identified, and use that to get suggestions for the unidentified photos?  If not, what might be some other tools we might use?


someone could explain to me this:   $$\int { \arctan { \left( \frac { 1 }{ { u }^{ 2 } }  \right)  }  }  \,du=\int { \frac { \pi  }{ 2 }  } -\arctan { \left( { u }^{ 2 } \right)  }  \, du$$

Verify the identity: $\tan^{-1} x + \tan^{-1} (1/x) = \frac\pi 2, x > 0$  $$\alpha= \tan^{-1} x$$  $$\beta = \tan^{-1} (1/x)$$  $$\tan \alpha = x$$  $$\tan \beta = 1/x$$  $$\tan^{-1}[\tan(\alpha + \beta)]$$  $$\tan^{-1}\left [{\tan\alpha + \tan\beta\over 1 - \tan\alpha \tan\beta} \right]$$  $$\tan^{-1}\left[ {x + 1/x\over 1- x/x }\right]$$  $$\tan^{-1}\left[{x + (1/x)\over 0} \right]$$  I can't find out what I'm doing wrong..


Let $T_\mathbb{R}$ be a real $n \times n$ matrix, and let $T_\mathbb{C}$ be the same matrix but considered as a complex one. What is the easiest way to see that $\min_{T_\mathbb{C}} \in \mathbb{C}[t]$ equals the image of $\min_{T_\mathbb{R}} \in \mathbb{R}[t]$ under the tautological map $\mathbb{R}[t] \to \mathbb{C}[t]$?

Like the title says, can a matrix in $\mathbb{R}$ have a minimal polynomial that has coefficients in $\mathbb{C}$?  I have a feeling the answer is yes because the characteristic polynomial can have coefficients in $\mathbb{C}$ and so I don't see any reason why not, I was merely asking in case there was some sneaky proof that proves that this cannot happen.


I want to ask a question on the music stack exchange about my voice and I'd like to upload and MP3? Is this possible?

I posted a question and a couple of respondents asked for the source code. I could only post portions of the code.  If attachments were allowed I could have uploaded a .zip file with the whole application.  Will this be a feature in SO?


When I add html dynamically, the new elements go without reference at event. For example:  function create() {     addButton(); } function addButton() {     let button = `<button type='button' class='btn btn-secondary'>Button</button>`;     $('body').append(button); }  $('button').on('click', create);  create(); create(); create();   This script results in 3 buttons. That when clicked adds a new button. But this new buttons when clicked nothing happens, because they have not referenced the "create" function when clicked.  Why?    The buttons that are created when the script runs, have "event". Those that are dynamically created do not.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


This code throws a NullPointerException.      protected static Integer cost; public static int incCost(int value) {    cost += value; };

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?


The goal is to do something every time a file from a list is modified (saved).  I have no idea to proceed. The end goal should be something like this:  files = ['file1.txt', 'file2.txt', 'file3,txt']  if (one of the files in files is modified):     Print '%s has been modified' % (filename)

I have a log file being written by another process which I want to watch for changes. Each time a change occurs I'd like to read the new data in to do some processing on it.  What's the best way to do this? I was hoping there'd be some sort of hook from the PyWin32 library. I've found the win32file.FindNextChangeNotification function but have no idea how to ask it to watch a specific file.  If anyone's done anything like this I'd be really grateful to hear how...  [Edit] I should have mentioned that I was after a solution that doesn't require polling.  [Edit] Curses! It seems this doesn't work over a mapped network drive. I'm guessing windows doesn't 'hear' any updates to the file the way it does on a local disk.


My project uses maven as the build tool, which works well so far.  I have a test module including all test cases of other modules, which is arranged under test/src/test/java/    However, when I create another module (let's call it TestB) and let it depend on the module test, all classes/interfaces defined in module test are invisible to the TestB. I wonder because I put all stuff under test/src/test/java but not test/src/main/java.  But if I move classes to test/src/main/java, the JUnit tool will stop working. Any good ideas on this?

How can you depend on test code from another module in Maven?    Example, I have 2 modules:   Base Main   I would like a test case in Main to extend a base test class in Base.  Is this possible?  Update: Found an , which involves creating a test jar.


Abstract:   Ubuntu detects wireless interface, but menu does not show any wireless network.  Details:  I have installed Ubuntu on MacBook pro early 2015. The appropriate drivers for my wifi are installed (according to this question ). My device is  ~$lspci -nn | grep 0280 03:00.0 Network controller [0280]: Broadcom Corporation BCM43602 802.11ac Wireless LAN SoC [14e4:43ba] (rev 01)   and it seems, that Ubuntu sees wireless interface  ~$ sudo lshw -C Network *-network                   description: Network controller    product: BCM43602 802.11ac Wireless LAN SoC    vendor: Broadcom Corporation    physical id: 0    bus info: pci@0000:03:00.0    version: 01    width: 64 bits    clock: 33MHz    capabilities: pm msi pciexpress bus_master cap_list    configuration: driver=wl latency=0    resources: irq:18 memory:c1400000-c1407fff memory:c1000000-c13fffff *-network    description: Ethernet interface    product: NetXtreme BCM57762 Gigabit Ethernet PCIe    vendor: Broadcom Corporation    physical id: 0    bus info: pci@0000:0a:00.0    logical name: ens9    version: 00    serial: ac:87:a3:38:54:a8    size: 1Gbit/s    capacity: 1Gbit/s    width: 64 bits    clock: 33MHz    capabilities: pm vpd msi msix pciexpress bus_master cap_list rom ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation    configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.137 duplex=full firmware=57762-a1.10 ip=130.223.51.185 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s    resources: irq:19 memory:cda00000-cda0ffff memory:cda10000-cda1ffff memory:c1a00000-c1a0ffff   Therefore I do not get, why the menu with possible connection does not show any wireless networks (only Ethernet cable). I also installed next to unity KDE, and in the both cases, the list is blanc.  I also tried to install what is recommended here,  but without any change of output (it is different wifi if I understood right, not wonder it has not worked).

Part 1  I upgraded 2012 MBA to 2015 MBPr (I loved Mint 17.1 Rebecca on the MBA but graphics/kernel issues means I need to wait till 17.2 to use Mint again)  I've managed to install Ubuntu on an SDcard. It boots and works. Great tutorial on this is .  I cannot get the Wi-Fi to work.  Used Terminal to determine the chipset:   $ lspci -nn | grep 0280 03:00.0 Network controller [0280]: Broadcom Corporation BCM43602 802.11ac Wireless LAN SoC [14e4:43ba] (rev 01)   I tried enabling the driver in Software & Updates → Additional Drivers. Ubuntu freezes so that's a no go.  I used terminal to install the following blobs/drivers (not sure what you call them) offline:  sudo dpkg -i bcmwl-kernel-source_6.30.223.248+bdcom-0ubuntu2_amd64.deb dkms_2.2.0.3-2ubuntu3_all.deb   This caused the system to freeze at:  DKMS: install complete   I rebooted and tried reinstalling using Ubuntu Software Installer which caused it to hang.  I've not messed with anything else. Can someone please explain what I am doing wrong?  Okay, here's part 2:  I tried installing bcmwl-kernel-source_6.30.223.30+bdcom-0ubuntu3_amd64.deb.  This is the error message:  Selecting previously unselected package bcmwl-kernel-source. (Reading database ... 170952 files and directories currently installed.) Preparing to unpack bcmwl-kernel-source_6.30.223.30+bdcom-0ubuntu3_amd64.deb ... Unpacking bcmwl-kernel-source (6.30.223.30+bdcom-0ubuntu3) ... Selecting previously unselected package dkms. Preparing to unpack dkms_2.2.0.3-2ubuntu3_all.deb ... Unpacking dkms (2.2.0.3-2ubuntu3) ... Setting up dkms (2.2.0.3-2ubuntu3) ... Setting up bcmwl-kernel-source (6.30.223.30+bdcom-0ubuntu3) ... Loading new bcmwl-6.30.223.30+bdcom DKMS files... First Installation: checking all kernels... Building only for 3.19.0-15-generic Building for architecture x86_64 Building initial module for 3.19.0-15-generic ERROR (dkms apport): kernel package linux-headers-3.19.0-15-generic is not supported Error! Bad return status for module build on kernel: 3.19.0-15-generic (x86_64) Consult /var/lib/dkms/bcmwl/6.30.223.30+bdcom/build/make.log for more information. modprobe: FATAL: Module wl not found. update-initramfs: deferring update (trigger activated) Processing triggers for man-db (2.7.0.2-5) ... Processing triggers for initramfs-tools (0.103ubuntu15) ... update-initramfs: Generating /boot/initrd.img-3.19.0-15-generic   I then tried:  $ sudo modprob wl sudo: modprobe: command not found   I checked and apparently the driver is recognized as installed:  ~$ sudo lshw -C Network *-network UNCLAIMED         description: Network controller    product: BCM43602 802.11ac Wireless LAN SoC    vendor: Broadcom Corporation    physical id: 0    bus info: pci@0000:03:00.0    version: 01    width: 64 bits    clock: 33MHz    capabilities: pm msi pciexpress bus_master cap_list    configuration: latency=0    resources: memory:c1400000-c1407fff memory:c1000000-c13fffff   So here I am, no Wi-Fi, not seeing any network ID...  I've Googled and found a few other people who've managed to get Wi-Fi working using the same blobs/drivers.  Can someone please shed light on why this is not working?  Also, why is the Apple Thunderbolt Ethernet Adapter not recognized, that thing came out years ago and it would make this processes a lot easier if I could at least get online to look up fixes, etc.


In my case I'm designing a rating system and want to discuss the benefit of using a 5-star system vs a binary up/down-vote - and might want to delve into technical aspects such as database representation, algorithms etc. Or I might wish to discuss things such as "gamification" concepts and how to incorporate them into my application, e.g. issues relating to application design. I haven't found any forum for these kinds of questions - is there such a site out there? I ask here because I'm guessing people here are most likely to be aware of such a site if it exist.  Also, it would be nice if such a stack-overflow site related to application design :).

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


Is there a word for exaggerating the pronunciation of a vowel or consonant by holding it longer than normal? When conveying this in writing, does it fall in the same category as an accent or dialect (even though it's neither) or are there other rules I should be aware of?   Examples:    Heeere's Johnny lllet's get ready to rumbllle   Halloooooooooooooooooo!

Is there a word or phrase for this? When you take a word and extend the sound of a letter - usually a vowel - to intensify it. Sometimes you might say Helloooo and stretch out the ‘o’ sound. What is this called?


Given an infinite field $K$, one can prove that any maximal ideal of $K[X,Y]$ can't be principal. In fact, every non-principal prime ideal is a maximal ideal, and can be generated by two polynomials. I am wondering whether the same result holds in $\mathbb F_q[X,Y]$. Can we find a principal ideal $I = (P(X,Y))$ for some irreducible polynomial $P$ that is a maximal ideal ?  Such a polynomial $P$ must have positive degrees in both $X$ and $Y$. Indeed, given an irreducible polynomial $Q(X)$ in only one variable, the quotient $$\mathbb F_q[X,Y]/(Q(X))\cong (\mathbb F_q[X]/(Q(X)))[Y]$$ is a ring of polynomials over a field and as such, can never be a field. Moreover, such a polynomial $P$ must have the form $$P(X,Y) = \sum_{i=0}^n P_i(X)Y^i$$ where $d\geq 1$, the $P_i$'s are polynomials in $X$ and $P_n$ is a nonzero polynomial that vanishes identically on $\mathbb F_q$, thus $P_n$ must be divisible by $\prod_{\alpha \in \mathbb F_q} (X-\alpha)$. Indeed, if there were some $\alpha \in \mathbb F_q$ such that $P_n(\alpha) \not = 0$, then the ideal $I:=(P,X-\alpha)$ would contain $(P)$ strictly. If $(P)$ were to be maximal, $I$ would be the whole of $\mathbb F_q[X,Y]$. Writing down the fact that $1\in I$ and evaluating $X=\alpha$ would leads us to the conclusion $n=\deg_Y(P)=0$, which is absurd. This is all I could infer so far. With respect to the above, I tried looking at $P(X,Y) = (X^{p-1}-1)XY - 1$ or $P(X,Y) = (X^{p-1}-1)XY - X - 1$ in $\mathbb F_p[X,Y]$ for some prime number $p$ but I have trouble determining whether the quotient is a field or not. Would somebody know the answer of the problem, and according to it, give a proof or a counter-example ? Thank you very much in advance.

Let $f$ be a nonconstant element of ring $\mathbb Z[x]$. Prove that $\langle f \rangle$ is not maximal in $\mathbb Z[x]$.   Let us assume $\langle f \rangle$ is maximal. Then $\mathbb Z[x] / \langle f \rangle$ would be a field. Let $a \in \mathbb{Z}$. Then $a + \langle f \rangle$ is a nonzero element of this field, hence a unit. Let $g + \langle f \rangle$ be its inverse. Then $a g - 1 \in \langle f \rangle$, hence $ag(x)-1 = f(x)h(x)$ for some $h \in Z[x]$, hence $ag(0) + f(0)h(0) = 1$, thus $(a,f(0))=1$ for all $a \in \Bbb Z$, contradiction, hence the proof.  Is my argument correct? Is there any other method?


import java.io.File; import java.io.FileNotFoundException; import java.util.Scanner;  public class testing {      public static int[] populationVectorFicheiro;     public static double[] survivalMatrixFicheiro;     public static double[] birthMatrixFicheiro;     public static double[][] matrizLeslieNaoInterativo = new double[survivalMatrixFicheiro.length + 1][birthMatrixFicheiro.length];      public static void main(String[] args) throws FileNotFoundException {         readFileInfo();     }      public static double[] formarVetor(String[] line) {         double[] matrix = new double[line.length];         for (int i = 0; i < line.length; i++) {             String[] numbers = line[i].trim().split("=");             matrix[i] = Double.parseDouble(numbers[i]);         }         return matrix;     }      public static double[] getValores(String[] linha) {         double[] matriz = new double[linha.length];         for (int i = 0; i < linha.length; i++) {             String[] objeto = linha[i].split("=");             matriz[i] = Double.parseDouble(objeto[1]);         }         return matriz;     }      public static int[] getTotalPopulacao(String[] linha) {         int[] matriz = new int[linha.length];          for (int i = 0; i < linha.length; i++) {             String[] objeto = linha[i].split("=");              matriz[i] = Integer.parseInt(objeto[1]);         }          return matriz;     }      public static void readFileInfo() throws FileNotFoundException{         Scanner fileReader = new Scanner(new File("caes.txt"));         String[] primeiraLinha = fileReader.nextLine().trim().split(",");         populationVectorFicheiro = getTotalPopulacao(primeiraLinha);          String[] segundaLinha = fileReader.nextLine().trim().split(",");         survivalMatrixFicheiro = getValores(segundaLinha);         for (int i=0; i< survivalMatrixFicheiro.length;i++){             System.out.println(survivalMatrixFicheiro[i]);         }           String[] terceiraLinha = fileReader.nextLine().trim().split(",");         birthMatrixFicheiro = getValores(terceiraLinha);          double[][] leslieMatrix = fillMatrix(survivalMatrixFicheiro,birthMatrixFicheiro);         printMatrix(leslieMatrix);      }      public static void printMatrix(double[][] matriz) {         for (int i = 0; i < matriz.length; i++)//Cycles through rows         {             for (int j = 0; j < matriz[i].length; j++)//Cycles through columns             {                 System.out.print(matriz[i][j] + " ");             }             System.out.println(); //Makes a new row         }     }       public static double[][] fillMatrix(double[] survivalMatrix, double[] birthMatrix) {          for (int i = 0; i < birthMatrix.length; i++) {             matrizLeslieNaoInterativo[0][i] = birthMatrix[i];         // preenche a primeira linha         }         int count = 0;         for (int i = 1; i < survivalMatrix.length + 1; i++) {             for (int j = 0; j < birthMatrix.length; j++) {                 if (i == j + 1) {                     matrizLeslieNaoInterativo[i][j] = survivalMatrix[count];                     count++;                 } else {                     matrizLeslieNaoInterativo[i][j] = 0;                 }             }         }         return matrizLeslieNaoInterativo;     }  }  I currently have this code in Java for some testing for a bigger project. I'm trying to create some public variables to use throughout my bigger project, but I keep getting an error while trying to use them here. Whenever I create a public matrix with other public variables as its parameters, I keep getting an error:  Exception in thread "main" java.lang.ExceptionInInitializerError Caused by: java.lang.NullPointerException: Cannot read the array length because "testing.survivalMatrixFicheiro" is null  Is there anyway to fix this? I need to keep that matrix as a public variable for other methods on the bigger project.


I am working on an exercise, at the end of which I need to show      $$\sum_{k=1}^{\infty}\dfrac{1}{k(\log k)^{1+\epsilon}}<\infty,\ \text{for}\ \epsilon>0\ \text{fixed}.$$   It is natural to try to get an upper bound of this series which converges, and as $k\geq 1$, we must have $$k(\log k)^{1+\epsilon}\geq (\log k)^{1+\epsilon},$$ and thus $$\sum_{k=1}^{\infty}\dfrac{1}{k(\log k)^{1+\epsilon}}\leq \sum_{k=1}^{\infty}\dfrac{1}{(\log k)^{1+\epsilon}},$$ but how could I show the latter series converges? does this series even make sense (since we have singularity at $k=1$)?  Thank you!

I came across a question about convergence tests and I'm not sure how to show that  $\sum_{n=2}^{\infty}\frac{1}{n \log(n)^p}$  converges for $p>1$. I found that the integral test works but I haven't learnt it yet. I have learnt the comparison test, so I tried that but couldn't find any series that converges to which I can compare. So my question is both how can I show convergence here with comparison test and also: Is there some list of convergent series that I can compare to? PS: I also found out that this is called a ln seriesAlso, this is not a duplicate of  question. (The power is on the $\log$ here)


How to prove $\sum\limits_{j=1}^{\infty}j(1-p)^j=\frac{1-p}{p^2}$?  Is there any general ways to think about this kind of problems?

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


Is there a C# method like Python's repr() to get the true representation of the object? Suppose we have:  string identifier = "22\n44"; Console.WriteLine(identifier);   This would return  22 44   Is there a way to get   "22\n44"   In Python this is easy. We can just do repr("22\n44").  I thought of this question because I was trying to convert "2244" to '2244' using   var identifier = "2244"; identifier = identifier.Replace("\"", "'"); Console.WriteLine(identifier);   The output is just 2244, because double quotes are for our purpose. But in my case, I  did this to get what I wanted:  identifier = string.Format("'{0}'", identifier);   because initially the database was receiving the query as IN ("2244") instead of IN ('2244') and was throwing Invalid Number error.

In C#, can I convert a string value to a string literal, the way I would see it in code? I would like to replace tabs, newlines, etc. with their escape sequences. If this code: Console.WriteLine(someString);  produces: Hello World!  I want this code: Console.WriteLine(ToLiteral(someString));  to produce: \tHello\r\n\tWorld!\r\n


If the value of the US dollar is greater than what I originally exchanged it for, is it considered capital gain? If so, how do I determine the amount I gained?  EDIT:  For example, I traded $100 USD for Mexican pesos. I spent some of that money (logically I now have less than $100 USD). But for some reason, the value of the peso skyrocketed so when I go to trade my remaining pesos for USD, I get back $1000.

I am an American and pay taxes in US dollars. I have some holdings in another currency, for instance, the Euro. Obviously the funds have never been repatriated but this lack of tax event is messing with my accounting.  From my basic understanding, the tax event would be long or short term capital gains solely based on my initial entry into the foreign currency, and then how many dollars I have when I liquidate that foreign currency. Simple enough.  This starts becoming complicated for me when I am also invested in shares of companies denominated in this currency. The trades and investing has been largely successful, but is it such an absolute that there is no US tax event for these foreign denominated trades?  We can ignore PFIC regulations for this question. I am only concerned about income tax, capital gains tax and dividend withholding for the US jurisdiction.  The way I understand it right now, the only tax event is the one that occurs when I liquidate the financial products AND bring the proceeds back to my US accounts, and where new total is more than what I began with (capital gain).   And all of this is compounded by the fluctuations in the exchange rate. I feel like I can't even estimate my taxes if I wanted to. So I can't be the only one that has ever faced this dilemma, I have no need to actually realize capital gains or repatriate, so are there accepted guidelines


I’m interning at a small software company and trying to set up a local server. I’ve found two old machines that are available for use, running Windows XP and Windows Server 2003.  However, no one knows the passwords for these machines. Is there any way to reset the user accounts without any OS installation discs?

I am trying get an unused server up and running, it booted fine but i was greeted with the login window and none of the known passwords seem to work. The server I am trying to get to work is not a Domain Controller and has not been used in a long time.  OS: Windows 2003 Server R2 Enterprise Edition  I tried Ophcrack XP (there is no WinServer version of Ophcrack) - it couldn't locate the partitions with hashes. I tried mounting the partitions myself (#mount /dev/hda*x* /mnt/ntfs), but it gave me an error saying /dev/hda*x* didn't exist.  Next I tried booting into a Ubuntu 10.04.3 LiveCD so that I could install and use chntpw - no go, Ubuntu Live wouldn't boot.  Based on what I've read up the following tools may be of help:   Windows Password recovery Petter Nordahl-Hagen's Offline NT Password & Registry Editor Openwall's John the Ripper EBCD – Emergency Boot CD - Bootable CD (R)ecovery (I)s (P)ossible Linux rescue system   I am hoping that someone here has prior experience with Win2k3 Administrator password resets so that I don't end up having to try all of the above to find out which one works.


Are there security upgrades when LTS is over, at least form unattended-upgrades?  That is, if I installed some Ubuntu and we reached some year and my LTS is over but I have an Ubuntu- server environment with sites online, should I still get any kind of security upgrades to my software from unattended-upgrades?  I am not aspiring to upgrade via apt-get update -y && apt-get upgrade -y unless when I install a new server environment, thus I'd be content from the minimal upgrades by unattended-upgrades.

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


Actually, h tags have margin:  h1, h2, h3 {     margin: 0 0 1em; }   But "Communities" block has class .gs4, which overides this rule:  .gs4 {     margin: -2px; }   Could you fix it?

From the     The spacing there between "Communities" and "This user doesn't participate in any other communities" looks a bit messed up... it's too small. Can we have that message shifted downwards a bit?  This alignment problem doesn't show up on profiles where there are other communities; on most profiles, even if the user isn't on any other sites, it'll list the present site anyways (i.e. for someone who's only on Meta SE, there'll be one entity, Meta, in that list, and everything looks fine).  This happens on all sites, and I've observed it on Vivaldi 2.0 and Chrome for Windows 10.


My Schengen visa was rejected in october 2018 stating:   Justification for the purpose and conditions of intended stay was not provided The information submitted regarding the justification for the purpose and conditions of intended stay was not reliable.   Kindly advise what went wrong. This was my first attempt for any visa application. I do not have any travel history and the reason I want to travel now is to redeem a travel voucher I was awarded by my employer.   So I do understand me not adding a cover letter was one of the biggest mistake. Secondly I think I submitted two bank statements...One is for my Salary transfer account where usually I do not maintain any balance and second was my savings account which I usually use for all my transactions.  So if I now attach the copy of travel voucher and cover letter and my salary account with a good balance and transactions for almost 4 months, will that help?

Schengen refusal formulae can be difficult to understand sometimes.  Sometimes an applicant receives a refusal with:       Justification for the purpose and conditions of the intended stay was not reliable.     often accompanied by:       Your intention to leave the territory of the Member States before the expiry of the visa applied for could not be ascertained.   What is meant by this refusal reason?  What are they trying to say?


I have a problem with identifying seasonality without using plots.  From what I have understood, the best way to detect seasonality in a time series is by understanding the data, plotting it and analyzing the autocorrelation plot. Now I would like to apply this process to sales data about multiple products from multiple companies, which means thousands of different time series. Since I cannot take the time to understand and plot data for every product, I would like this process to become "automatic". Automatic in the sense that there would be a data pipeline where, amongst other things, there will be a seasonality test and then a seasonal difference (if seasonality is detected) etc... Just so you can understand: the pipeline's final goal is to return forecasts. That is why I am trying to make my data stationary.  I don't think plot analysis is possible (or, at least, easy to implement for a beginner like myself) in such a pipeline. Therefore I cannot rely on it. So my question is: Are there any non-graphical tests that I can use in order to detect seasonality ? I have looked into Ljung-Box but it seems that it is only used for residual analysis when fitting models, which is not what I am looking for. Thank you for your help!

I want to test if my series is seasonal, here pacf and the series I'm working on monthly data. is there a test under R seasonality?


I have a thinkpad yoga s1 with i7 cpu, hd4400 graphic card and Ubuntu 14.04.01 installed. The computer freezes when closing lid but if I suspend it before I close the lid, it won't freeze next time when I open the lid.  I've tried everything I can. I already updated the graphic card driver with the software provided by intel. Nothing changed. Any help please?

I would like closing the laptop lid to be a no-op. How can I do that?


I opened  which has been closed as a duplicate. Prior to being closed it had received a single answer. After I had loaded the page an edit was made to that answer, resulting in the notification/live refresh link ("an edit has been made to this answer; click here to refresh") appearing at the top of the answer.  Upon clicking on the link to refresh the answer, the answer was updated (as expected) but the box containing the list of duplicate questions ("This question already has an answer here:") and the close reason were removed from the page.

I've come across a small issue which occurs when a question has been closed but the question itself or one of its answers are being edited.  Steps to reproduce:   Visit a closed question. (even closed years ago)   In a different tab or browser, edit the question or one of its answers. "an edit has been made to this post; click to load" message will appear above the edited post in the first tab/browser, click it. The .question-status div becomes hidden, which includes the closed notice below a question and, for a duplicate-closed question, the list of duplicates above the question body. This gives the appearance that the question is no longer closed (until you refresh).   Some screenshots:                I know it isn't common/important but it did confuse me when looking at a particularly bad question - I thought it had been reopened.   Is this an intentional feature? If so, what was the thinking behind it?    Another example  Before    After


Let $f:\mathbb{R^2} \to \mathbb{R}$ and $\partial_1f(x,y)=0, \partial_2f(x,y)=0$ for all $x,y \in \mathbb{R^2}.$ Show that $f$ is a constant function.  From the problem statement I got that $\nabla f(x) = (\partial_1f(x,y), \partial_2f(x,y)) = (0,0).$ And now $$f(y)-f(x) = \nabla f(x)\cdot(y-x)+||y-x||\varepsilon(y-x)$$ which will result in $$f(y)-f(x)=0\cdot(y-x)+||y-x||\varepsilon(y-x) =||y-x||\varepsilon(y-x).$$ What should I do with the term $||y-x||\varepsilon(y-x)$ that I'm left with? By the definition $\varepsilon(y-x)$ goes to $0$ when $y\to x$, but how do I show this?

Let $f(x,y)$ be a function of two variables. Given that  $$\frac{\partial f}{\partial x}=0$$ for all $y$, and  $$\frac{\partial f}{\partial y}=0$$ for all $x$, is there a theorem that states $f(x,y)=$ constant for all $x$, $y$? Or how would I prove this rigorously?


In the image i have 5 rock at one side and a single red mark rock. I have done uv mapping to the red mark rock. I want the texture of the red mark rock on all rest of the 5 rocks. I have applied the material to the 5 rocks but the texture not applied. Im in cycle render now. How to get the texture on rest of the rocks

I've got two objects that are exactly the same, but with different UVs, is there any way to transfer the UV from one to another?


I have imported data from excel sheet to mysql and phpmyadmin is showing data in correct encoding or you can say in a readable form like  51cm (20¼”) 41cm (16¼”)   However when i try to display this data in my application it is displaying it as  51cm (6Â½â)   i think there is problem with " this symbol....  How can I fix this.. I have already tried using  htmlspecialchars_decode()  html_entity_decode()   but no solution so far.. Any help will be deeply appreciated. Thanks ...

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I found two or three times that someone was a ♦ moderator on a specific site in the SE Network, but now is not a moderator.  Can moderators resign?  Is it also possible for a moderator to be dismissed if many violations/complaints are made?  Or if a moderator is inactive for a long time will that cause dismissal?

After a site is graduating, its moderators appear to be elected for life or until they step down.  What are the steps for recalling a moderator that the site's users no longer believe represent the site's best interests?


my question it's because previously i tried to install windows 10 on external ssd but it doesn't work correctly so, i wonder if ubuntu 20 or linux mint have the same problem. Actualy, i use dual boot with Ubuntu 20 and windows 10, but i have been thinking on use completely Ubuntu 20

what I want to do is this. I have an external hard disk drive, a SEAGATE expansion 1TB, you can take it a look here:  As you can see this is not a flash usb hard drive, it is a USB hard disk drive. What I want to do is installing Ubuntu in this external hard disk drive... BUT NOT PLACING THE GRUB ON MY C: DRIVE. In other words, I don't want to see the GRUB splash Window asking me every single time if I want to load Windows or Linux. I want my PC turn on or restart and go directly to Windows... BUT... I want to have Linux in my external USB hard disk drive How do I want to load Ubuntu then? Easy, when I restart my computer or just start it... in ASUS mother boards I have the possibility to select the boot device by pressing F8, and I get the boot menu. I want to turn on my computer, press F8, my mother board ask me what drive I want to use to load the Operating Sytem, I select the USB external hard disk drive where do I have Ubuntu, and bingo, I run Ubuntu. When I finish to use Ubuntu, I close it and turn off my computer. Later, I turn on my computer, and if I don't press F8, automatically load the hard disk drive C: and load Windows. My question about this, is what are the necessary steps to install the latest version from Ubuntu, doing exactly this. Not placing the GRUB in my C: hard disk drive, and installing it entirely in the external USB hard disk drive (normal one, not flash one).


I want to execute file ex from my memory stick with FAT file system. I typed:  /media/user/844E-0486$ sudo chmod 777 ex   However still I haven't got permission to execute it.   /media/user/844E-0486$ ls -l total 8 -rw-r--r-- 1 user user    0 lut 18 17:46 ex drwxr-xr-x 2 user user 8192 lut 18 17:44 System Volume Information   Is there any way to run it?

I'm trying to install a portable app onto my USB drive such that it is compatible with both Ubuntu and Windows (specifically, a program called eToys). Support is already built into the app for both operating systems - there's etoys.sh for Ubuntu and etoys.exe for Windows. I decided to install onto a FAT drive since that can be read from both systems. This works fine for Windows, but for some reason I cannot execute etoys.sh on Ubuntu.  The problem is not with the file - when the whole folder is copied to the local hard drive, the app works great in Ubuntu. But when I try to execute it from the USB, it opens the file in a text editor.  I then tried to run it from a terminal, but I got the message Permission denied.  I've had the same problem with other executables as well.  Is there an easy way to execute things from a USB stick?


I have a question regarding model selection based on the AIC criterion. I have 5 predictor variables that I include in my models (no interactions are included) and create all possible model combinations. After, I calculate the AIC values for each model and thought I should select the model with the lowest AIC value, which already penalizes for the number of parameters included. However, when I test between the model with the lowest AIC value (that contains four parameters) and the second lowest AIC value (that contains three parameteres) using the anova() function in R, it seems that the preferred model is the one with the second lowest AIC value (three parameters) because it seems that the more complex model is not explaining significantly greater variance than the less complex model, even if the former has the lowest AIC value. I'm confused as to what model should actually be selected. Can someone clarify this discrepancy for me?

The software that I am currently using to build a model compares a "current run" model to a "reference model" and reports (where applicable) both a chi-squared p-value based on likelihood ratio tests and AIC values for each model.  I know that one advantage of AIC over likelihood ratio tests is that AIC can be compared on non-nested models.  However, I am not aware of any reason why AIC couldn't or shouldn't be compared on nested models.  In my model, when comparing nested models for variable selection, I'm finding several cases where the likelihood ratio test and the AIC comparison are suggesting opposite conclusions.  Since both are based on likelihood calculations, I'm struggling to interpret these results.  However the documentation of my software says (without explaining),   "If two models are nested (i.e. one is a sub-set of the other) then the more usual chi-squared test is the most appropriate to use. If the models are not nested, the AIC can be used..."  Can anyone elaborate on this and/or explain why AIC is not as helpful as likelihood ratio tests on nested models?


I assume, that Stack Exchange have some clean-up subsystem, which deletes all "abandoned" images (stored at i.stack.imgur.com), that is, all of them, that were initially uploaded, but no post is actually having link to them. Am I right?  If such subsystem is implemented and is doing its job on regular basis, then what about following scenario:   Start a new question or answer, anywhere. Hit button and upload an image. Copy generated image's URL  to clipboard. Close tab and drop editing post. Go to question on answer, you actually planned to reply. Post a comment to it and paste copied image's URL from clipboard to comment's body.   Will uploaded image, with URL pasted only to comment, be kept permanent? Does clean-up subsystem (if exitst) take care of checking for image's URLs in comments as well?

. I did a trick:  I clicked on "Ask Question" here on Meta Then I clicked the icon "Add image" I uploaded the image from my computer and copied the link  I pasted the link to the comment I discarded the question.  Is this a clean and correct approach? An example thought why this possibly wouldn't be clean: Is the image hosted permanently? There could be, in theory, some "garbage collector" that would delete all images that are not linked from within any question (well, mine is now linked from this question, though not normally - funny enough right :-)).


I marked the problem i cant install with ubuntu center and Synaptic i cant repair !!   The following packages have unmet dependencies: wine1.6: Depends: wine1.6-i386 (= 1: 1.6.1-0ubuntu1 PPA1 ~ ~ precise1) but it is not installable E: Unmet dependencies. Try 'apt-get f install' with no packages (or specify a solution).  64 bit 12.04LTS  and tried update to ubuntu 14.04 but I cant update too..

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


Here's an email I just received for a tag I subscribe to, showing a summary of a new question asked:  Creating tree formed XML from flat XML with Xquery  I have some XML in the following format:   &lt;data&gt; &lt;row&gt; &lt;id&gt;1&lt;/id&gt; &lt;parent_id/&gt; &lt;/row&gt; &lt;row&gt; &lt;id&gt;2&lt;/id&gt; &lt;...  tagged: xml, xquery Sep 7 at 13:46   (The link to this question is .)  The escaped angle brackets make the summary harder to read.  Ideally, the summary would show the text as is:  I have some XML in the following format: <data> <row> <id>1</id> <parent_id/> </row>...   As a subscriber to XML-related tags, this would be great!

When I receive emails for my Stack Exchange email subscriptions, characters like < and > are doubly encoded, i.e., they are rendered as &lt and &gt (and encoded as &amp;lt; and &amp;gt;):    Here is a sample of the source for the same email:  <p style="font-size:100%;color:#3d3d3d;margin-top:5px">     I would like to change the following code so as to handle grouping of more than 1 property     private Expression&amp;lt;Func&amp;lt;ProfileResultView, string&amp;gt;&amp;gt; DynamicGroupBy(string propertyName)     {          ...  </p>


I try to automate a page that I have. In the page I need to upload a PDF file. The problem is that I want selenium via java will get the file from the resource of the project and not hard coded. (since some have windows and some mac and some ubonto so the solution is to get the path dynamically). I manually hard coded I enter the path it worked and return the path, however to let java return the path it crash. this is my code:   /******* test *******/     public  void testFileUpload() throws Exception {         WebDriver deiver2 = getWebDriver();                 Thread.sleep(3000);         deiver2.switchTo()                 .activeElement();         deiver2.findElement(By.xpath("//input[@type='file']"))         .sendKeys(                 "X:\\project\\src\\test\\resources\\TAX12.pdf");          ClassLoader classLoader = getClass().getClassLoader();         String path = classLoader.getResource("TAX12.pdf").getPath();         System.out.println("\n\n path is  " + path);          System.out.println("END");      }  I want in the send keys to send the file, the exists however it is not worked. java.lang.NullPointerException      at org.testng.Assert.fail(Assert.java:97)     at tests.ExPubPaymentPageTest.tryFile(ExPubPaymentPageTest.java:58)     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)     at java.lang.reflect.Method.invoke(Method.java:498)     at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:134)     at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:597)     at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:173)     at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)     at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:816)     at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:146)     at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)     at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)     at java.util.ArrayList.forEach(ArrayList.java:1259)     at org.testng.TestRunner.privateRun(TestRunner.java:766)     at org.testng.TestRunner.run(TestRunner.java:587)     at org.testng.SuiteRunner.runTest(SuiteRunner.java:384)     at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:378)     at org.testng.SuiteRunner.privateRun(SuiteRunner.java:337)     at org.testng.SuiteRunner.run(SuiteRunner.java:286)     at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53)     at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96)     at org.testng.TestNG.runSuitesSequentially(TestNG.java:1187)     at org.testng.TestNG.runSuitesLocally(TestNG.java:1109)     at org.testng.TestNG.runSuites(TestNG.java:1039)     at org.testng.TestNG.run(TestNG.java:1007)     at com.intellij.rt.testng.IDEARemoteTestNG.run(IDEARemoteTestNG.java:66)     at com.intellij.rt.testng.RemoteTestNGStarter.main(RemoteTestNGStarter.java:109)  the file exists in the folder and worked if manually set the path, but not locate the file if I want it to do it by himself (for win / mac / linux etc)

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?


Does anybody know if there is a conversion chart showing where stuff was and where it is now on the user interface, please? I have taken ages to learn Blender 2.7 and now I have to learn where everything is again. At the moment I'm about ready to forget 2.8 and just stick with 2.79.  Dave

Cannot find Background Images feature to add in a photo in Blender 2.8  Where is it?


I am writing an introduction, and I need to put my name at the end of it at the right side of the page, but it should be aligned left:  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem I psum has been the industry's standard dummy text ever since the 1500s, when an  unknown printer took a galley of type and scrambled it to make a type specime n book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s w ith the release of Letraset.                                                                    Andriy D.                                                                   Toronto, 2009   What is the best way to achieve this? Any tips appreciated!

I would like to put an address in my document as follows:  |                             | |                     Name    | |                     Street #| |                     City    | |                     ZIP     | |                             |   where the | mark the left and right page borders. I would like the items of the address (Name, Street etc.) to be left-flushed, but the box right-flushed so that the longest item touches the right page border.  Is there a simple way to accomplish this?


My claim is $O(4)\ncong SO(4)\times C_2$, since there is no "$-I$" role as in the proof that $O(3)\cong SO(3)\times C_2$, as $\det(-I)=1$ in $\mathbb{R}^4$. However, I cannot proceed like $O(2)$ case that both $SO(2)$ and $C_2$ are abelian while $O(2)$ is not. Are there any properties I missed?

This question is taken directly from Artin's "Algebra", on page 150:  Is $O_{n}$ isomorphic to the product group of $SO_{n} \times \{\pm1\}$?  Here, $O_{n}$ is defined as the group of orthogonal matrices, $SO_{n}$ is the special group of orthogonal matrices (i.e. orthogonal matrices which have determinant or $1$ or $-1$).


I just became a 10k user over at maths.SE, and now I see deleted answers, but I don't want to see them. (They're distracting.)  How do I ignore deleted answers? If there's not already a non-contrived way of achieving this, would it be possible to add a "[.] hide deleted answers" switch in the prefs tab (or something similar)?

Today I exceeded 10K reputation on Stack Overflow, and I see deleted answers.  I am now faced with pages like  where half the answers are "deleted."    Among these are many non-answers deleted by diamond moderators, and a self-deleted answer deleted on Nov 25 '09.  I find this very distracting, especially in my chosen sort order of "oldest" where these deleted answers are NOT displayed at the bottom.  I wish to be able to hide deleted answers based on combinations of characteristics such as:   age since deletion deleted-by-owner deleted by diamond moderators zero undelete votes   This would be a setting every user could enable for himself.    Here are HTML excerpts that may be useful for userscript filtering.  This shows the code that appears for a moderator deletion, as well as the date stamp.
deleted by Dori♦ Jun 26 at 9:13
   Here is the same class for deleted by owner:
deleted by owner Nov 25 '09 at 19:12


I'm trying to create a class from a singleton class using reflection, but it doesn't work. My SingletonClass looks like this.  public class SingletonClass implements IHashBehaviour { private static SingletonClass singleTon=null;  private SingletonClass () {     // TODO Auto-generated constructor stub }  public static synchronized SingletonClass newInstance(){     if(singleTon == null){         SingletonClass .singleTon=new SingletonClass ();     }     return singleTon; } }  public static SingletonClass create(SingletonClassType type){     SingletonClass obj=null;     Class<?> c;     try {         c = Class.forName(type.getFullQualName());         obj=(SingletonClass)c.newInstance();     } catch (ClassNotFoundException e) {         // TODO Auto-generated catch block         e.printStackTrace();     } catch (InstantiationException e) {         // TODO Auto-generated catch block         e.printStackTrace();     } catch (IllegalAccessException e) {         // TODO Auto-generated catch block         e.printStackTrace();     }     return obj; }   The method getFullQualName returns the package, like this "model.SingletonClass". I understand why this won't work because in the factory, the newInstance method looks for the default constructor but that one is private. i need to call the newInstance method from the Singletonclass itself.

If I have two variables:  Object obj; String methodName = "getName";   Without knowing the class of obj, how can I call the method identified by methodName on it?  The method being called has no parameters, and a String return value. It's a getter for a Java bean.


I want a bash command that I can pipe into that will sum a column of numbers. I just want a quick one liner that will do something essentially like this:  cat FileWithColumnOfNumbers.txt | sum

I am looking for a command that will accept (as input) multiple lines of text, each line containing a single integer, and output the sum of these integers.  As a bit of background, I have a log file which includes timing measurements. Through grepping for the relevant lines and a bit of sed reformatting I can list all of the timings in that file.  I would like to work out the total. I can pipe this intermediate output to any command in order to do the final sum.  I have always used expr in the past, but unless it runs in RPN mode I do not think it is going to cope with this (and even then it would be tricky).  How can I get the summation of integers?