Describe each of following the rings:   a) $\mathbb{Z}[x] / (x^2 - 3, 2x + 4)$      b) $\mathbb{Z}[i]/ (2 + i)$  a) Well, $\mathbb{Z}[x]$ is the set of all polynomials with integer coefficients and $(x^2 - 3, 2x + 4)$  is the ideal generated by two polynomials. I know that  $\mathbb Z[x] / (x^2 - 3, 2x + 4) = \{ r + (x^2 - 3, 2x + 4) : r \in \mathbb{Z}[x] \}$   b) I know that $\mathbb{Z}[i]$ is the set of all polynomials with the complex number $i$ as its variable. $\mathbb{Z}[i]/ (2 + i) = \{ r + (2 + i) : r \in \mathbb{Z}[i] \}$.   I already know that b) is $\mathbb Z$ modulo 5. What would a) be?

This problem is from a practice exam I was working on.     What is the cardinality of the quotient $\mathbb{Z}[x]/(x^2-3,2x+4)$ ?   Thoughts. If I find a ring that is easier to handle then this then I can go from there. So I think this is isomorphic to $\mathbb{Z}_2[x]/(x^2-3,x+2)$. And then I am stuck.  Am I correct so far? What should I be looking to do from here?  Thanks for your time and your answers.


After finishing Blender Guru's both doughnut and anvil tutorials I conceived that I should keep mesh quad-only. Moreover, all edges of my final meshes were looping, which I took as a rule too. But is there such a rule or how strong this rule is? Sometimes I end up with meshes like on the picture below, where all the faces are quads, but not all edges are looping. How bad is it?    More specifically, should I keep all vertices always connect four other?

Tris are things you would avoid when it comes to shading, and good Topology, so do Tris do any good? Also I am currently working on Game Asset Creation and I would like to know if Tris are actually something I want definately to avoid.


tick the first box appears in the following paragraph. What does it mean? Could you say it in other words?  SO IS THIS A REACTIVE APPLICATION? This is a very good question to ask. It is important to remember that while Vert.x is a toolkit for building reactive applications, using the Vert.x API and modules does not “auto-magically” make an application a reactive one. Yet the event-driven, non-blocking APIs that Vert.x provides tick the first box.

I came across the following example:     Tick the box if you would like more details.   In the sentence, "tick the box" means mark the specific checkbox. If we have the following checkboxes    ticking the first checkbox means selecting it.   But what is the difference between checking the box and ticking the box? Can I assume that the phrases are equivalent?


Is it possible to grep inside a bunch of archives with regular expressions on both the names of the files they contain and the contents of those files? I would like to know which files in which archives match the pattern. I'm on OS X, if it matters.

I'm trying to find out what modules  in cpan. So I've used  to mirror it. My problem is that I need to iterate through the archives that are downloaded, and grep the files that are in the archives. Can anyone tell me how I might do this? preferably in a way that tells me which file in the archive and what line it's on.  (note: they aren't all tarballs some are zip files)


I found a strange error in in_array() PHP function.  Next code returns TRUE but it's wrong value. Anyone can told my what I do wrong?  <?php var_dump(in_array(0, array('a', 'ab', 'abc')));   Live demo:   Of course I know that I can execute in_array(0, array('a', 'ab', 'abc'), true) but why without this true this function isn't working good.

What is the difference between == and ===?  How exactly does the loosely == comparison work? How exactly does the strict === comparison work?  What would be some useful examples?


I get the error below while trying to intall Oracle Java 8. Please tell me what's wrong.  $ sudo apt-get install oracle-java8-installer [sudo] password for pragya:  Reading package lists... Done Building dependency tree        Reading state information... Done Package oracle-java8-installer is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'oracle-java8-installer' has no installation candidate

I want to install Oracle's JRE and to update to the latest version with the Software Updater when they released. Is there a Ubuntu package that is provided by Canonical or Oracle?  Before release Java 7, I followed  to install Java 6.  But it doesn't work for Java 7. There is no package sun-java7-xxx. How can you install Java 7?


Is there a way to go through different commits on a file.  Say I modified a file 5 times and I want to go back to change 2, after I already committed and pushed to a repository.  In my understanding the only way is to keep many branches, have I got that right? If I'm right I'm gonna have hundreds of branches in a few days, so I'm probably not understanding it really.  Could anyone clear that up please?

I have made some changes to a file which has been committed a few times as part of a group of files, but now want to reset/revert the changes on it back to a previous version.   I have done a git log along with a git diff to find the revision I need, but just have no idea how to get the file back to its former state in the past.


A lot of time when I delete a folder, it says cannot be deleted because of .nfs files.  Error - Device or resource busy   How can I delete a folder ignoring these errors (is there any flag in rm command)? Or I would have to find out the process using it, and first kill that process?  In that case how can I make it work to remove entire directories?

I removed a file and now I see:  $ ls total 64 -rw-rw-r-- 1 502 17229 Sep 17 16:42 page_object_methods.rb drwxrwxr-x 7 502   238 Sep 18 18:41 ../ -rw-rw-r-- 1 502 18437 Sep 18 18:41 new_page_object_methods.rb -rw-r--r-- 1 502 16384 Sep 18 18:42 .nfs0000000000b869e300000001 drwxrwxr-x 5 502   170 Sep 21 13:48 ./ 13:48:11 *vagrant* ubuntu-14 selenium_rspec_conversion   and if I try to remove it:  $ rm .nfs0000000000b869e300000001 rm: cannot remove ‘.nfs0000000000b869e300000001’: Device or resource busy   What does this indicate?  What should I do


I have exported an Android Unity project to create and Android Studio project (as detailed here: )   While, the project will now run through Android Studio, I am unable to load an Activity which I created after importing the project.  I am wondering is this possible?  I have checked other solution for NullPointerException when calling a new class in android and was unable to see any relating issues, making me question if my approach to this problem is correct  The unity project is a simlple button that will access a method in the UnityPlayerActivity (proved through Log), before attempting to load the new activity AndroidTestActivity, which just contains a TextView.  Code is as follows  Unity C#:  public void Click () {      Debug.Log("Clicked");      AndroidJavaObject jo = new AndroidJavaObject("com.Test.AndroidTest.UnityPlayerActivity");     jo.Call("Created"); }   UnityPlayerActivity.java  public void Created(){     Log.e("tag", "Created");      Intent i = new Intent(this, AndroidTestActivity.class);     this.startActivity(i); }   LogCat Output:  E/tag: Created E/Unity: AndroidJavaException: java.lang.NullPointerException: Attempt to  invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference      java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference          at android.app.Activity.startActivityForResult(Activity.java:4400)          at android.app.Activity.startActivityForResult(Activity.java:4358)          at android.app.Activity.startActivity(Activity.java:4682)          at android.app.Activity.startActivity(Activity.java:4650)          at com.Test.AndroidTest.UnityPlayerActivity.Created(UnityPlayerActivity.java:39)          at com.unity3d.player.UnityPlayer.nativeRender(Native Method)          at com.unity3d.player.UnityPlayer.c(Unknown Source)          at com.unity3d.player.UnityPlayer$c$1.handleMessage(Unknown Source)          at android.os.Handler.dispatchMessage(Handler.java:98)          at android.os.Looper.loop(Looper.java:154)   I have also ensured that the new activity is declared in the android manifest and it has been imported in UnityPlayerActivity

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


I have just installed a citation manager Zotero using snap. I added one of AddOns called Zotfile to locally manage PDFs instead of storing them on a cloud. I configured Ubuntu such that my Documents are on mounted partition. I also use LVM. Within Zotero, when I try to configure the AddOn Zotfile and point at one of the folders on a mounted partition, I get permission error. When I use any local folder on the same partition, everything's OK. How can I solve the problem? I am confused because Zotero is installed by root and has root:root permissions.

I have Ubuntu 18.04 LTS installed. I inserted USB-flash to my laptop. It was automounted to /media/username/DISKLABEL and opened in Nautilus. I can read and write objects to it. How can I access it from the application, which is installed as Snap? I tried snaps of the following applications such as gedit, arduino-mhall119, organize-my-files. All them show me errors if I navigate to /media folder:    Could not read the contents of Media Error opening the directory of '/media': permission denied  Output of active Snap  is below: $ snap interfaces  | grep -v ".*-$" Slot                             Plug :browser-support                 organize-my-files :core-support                    core:core-support-plug :cups-control                    gedit :desktop                         gedit,organize-my-files :desktop-legacy                  gedit,organize-my-files :gsettings                       gedit,organize-my-files :home                            arduino-mhall119,gedit,organize-my-files :network                         arduino-mhall119,gedit,organize-my-files,pulsemixer :opengl                          organize-my-files :pulseaudio                      organize-my-files,pulsemixer :unity7                          arduino-mhall119,gedit,organize-my-files :wayland                         gedit :x11                             arduino-mhall119,organize-my-files,pulsemixer gnome-3-26-1604:gnome-3-26-1604  gedit gtk-common-themes:gtk3-themes    gedit gtk-common-themes:icon-themes    gedit gtk-common-themes:sound-themes   gedit -                                arduino-mhall119:serial-port -                                gedit:avahi-observe -                                gedit:mount-observe  Updates:  connecting mount-observe to Gedit with snap connect gedit:mount-observe does not help. it seems that we need special Snap with support of  interface.


I'm working through an old qualifying exam problem, and I'm stuck:     Let $R \neq (0)$ be a finite ring such that for any element $x \in R$ there is $y \in R$ with $xyx = x$. Show that $R$ contains an identity and that for $a,b \in R$ if $ab = 1$ then $ba=1$.     On first glance, I suspected that $xy$ is a perfectly good identity, but this doesn't work. For example, in $\mathbb Z_6$, if $x = 3$, then $y \in \{1, 3, 5\}$ works, but $xy = 3 \neq 1$.  Once I have solved the first part, I can do the second part, using an argument from .

Let $R$ be a finite ring such that for any $x \in R$ there exists $y \in R$ with $xyx = x$. Show that $R$ is unital and that if $ab = 1$, then $ba = 1$.   Thoughts so far: If I can show that the Jacobson radical is trivial, then I see how to get the result (since then it would be semi-simple, therefore equal to a direct product of matrix rings over division rings, hence equal to a direct product of matrix rings over fields (since the division rings would be finite), and this satisfies the property. So I'm wondering about how to prove that $J(R)$ is trivial. Any hints?


Assume by contraposition, there was a homeomorphism $f:S^2 \to \mathbb{R}^2$ (hint: there isn't). Let $x_0 \in S^2$. How does one show that under this hypothesis, $f$ implies the existence of a homeomorphism $f_0:S^2 \setminus \{x_0\} \to \mathbb{R}^2 \setminus \{f(x_0)\}$ ? $S^2 \setminus \{x_0\}$ is still path-connected...

I am trying to show that the sphere $S^2$ and $\mathbb{R}^2$ are not homeomorphic.I understand that you can't 'compress' a 3D shape into a 2D plane but I don't know how I would express this formally.  $S^2 = \{(x, y, z) ∈ \mathbb{R}^3: x^2 + y^2 + z^2 = 1\}$  As always, any help is appreciated!


I am experimenting with the multithreading in java and I have a nullPointerException. I try to pass a parameter in my thread and i missed up somewhere but i dunno where. I hope someone can point me where i was stupid :). I wrote this class :   public class MyThread extends Thread{  private String myBelovedParam = null;  public MyThread (String param){     myBelovedParam = param; } public void run(){     try {         AnotherClass.anotherFunction(myBelovedParam );      } catch (InterruptedException e) {         e.printStackTrace();     } }}   And I called it like that :  Thread myThread = new MyThread (theParameterIWant);     myThread.start();   Thanks all and have a good day !  I edit my post (i change the name of everything and i forgot to change some. that why the name of some thread was different).  Here is the error i get in my console :  Exception in thread "Thread-7" java.lang.NullPointerException at play.classloading.enhancers.ControllersEnhancer$ControllerInstrumentation.isActionCallAllowed(ControllersEnhancer.java:187) at anotherFunction(AnotherClass.java) at threads.myThread.run(myThread.java:21)   I tried to change null by empty String -> no Effect When i debug i can see clearly that theParameterIWant is not null.


I'm using /tellraw to make myself be happy for my map on some of the stuffs i needed for command blocks, but I can't do some of the Multiple colors and text like from the other maps with the names "" and using colored chat. (By the way DrStranger is just an example, but I still need some help thou.)

how can you put color on signs?,tried the color symbol (§) but it did not copy. also tried NBT tags such as {Color:"blue"} and it did not work ):!


The following comes from page 3 of the paper "Matrix Concentration for Products" found here . Given two independent, complex, square matrices Y and Z: $$ YZ=\mathbb{E}(Y)Z+(Y-\mathbb{E}(Y))Z.$$ I understand that $$ \mathbb{E}((Y-\mathbb{E}(Y))Z|Z)=0. $$ Now, this is called an orthogonality property (Why?) and apparently used to show: $$ \mathbb{E}(\left\| YZ\right\|_2^2) =\mathbb{E}(\left\|(\mathbb{E}(Y))Z\right\|_2^2) + \mathbb{E}(\left\| (Y-\mathbb{E}(Y))Z\right\|_2^2) $$ where $\left\| .\right\|_2$ refers to the Schatten 2-norm or Frobenius-norm. Could someone clarify how exactly this property is used here? I assume the tower property comes into play here but I'm not sure how exactly. Thank you.


scheduleClient = new ScheduleClient(mContext); scheduleClient.doBindService(); Calendar cal=Calendar.getInstance(); cal.setTime(date); scheduleClient.setAlarmForNotification(cal);   I can't see where is the problem as I have initialized the object. Rhis is the error which I am getting.  java.lang.NullPointerException: Attempt to invoke virtual method 'void lol.com.epl.ScheduleService.setAlarm(java.util.Calendar)' on a null object reference         at lol.com.epl.ScheduleClient.setAlarmForNotification(ScheduleClient.java:63)         at lol.com.epl.FixAdapter$1.onClick(FixAdapter.java:128)   java:128 points to line  scheduleClient.setAlarmForNotification(cal);   At line 63    public void setAlarmForNotification(Calendar c){      mBoundService.setAlarm(c); }


I read this story in the last 10 years. It is a scifi short story, probably published in Giganotosaurus or some other sci fi short story collective. Definitely published online.   The story is kind of like "The Entire History of You" from Black Mirror, where people's whole lives are recorded by small devices. Except the conceit in this story is that everyone's "talent" at different things (think... everything from juggling to cooking) is ranked, and social value and popularity is derived from this.  So this leads to a bunch of people trying to find the obscure thing that they can climb the rankings in (I seem to remember the protagonist was at one point in the top 500 Male jugglers under 30 or something like that). Then one day, he has sex, and is suddenly the number 1 Male Lover in the world. I think this happens, at least.  Later on, he finds a community who has given up the devices, and finds joy in doing things even though they aren't the best at them. I remember the girl being impressed by his juggling (?) "even though he isn't even in the Top 100", and the love interest's lack of world-weariness enlivens the protagonist.  Thank you to anyone who ended up reading this!

This is a recent story, probably from the 2000s.  The protagonist of the story is a teen-aged boy whose highest "rating" (based on the entirety of the world population) is in... magic, or card tricks, or something to do with cards? He laments he will never really be good enough to be famous/popular and have a shot at being in the Top 100, etc. Eventually he meets a girl who is disconnected from the "system," and when he shows her his card tricks, she is impressed because she has never seen anyone do it better, since she isn't a part of the "system."   There was a part in the story talking about how one kid who had never had sex before, had sex with someone else and instantly became the #1 rated "male intercourse with female" in the world, and how everyone was waiting for him to have sex again to see if his rating would stay high or plummet out.  I don't remember if the story was CCTV-style constant surveillance or 'eye cam' or both. I do remember that the protagonist and the girl had to go somewhere secluded (and take out their contact-cam?) to get away from being recorded.


I'm tired of bloatware on my amazon fire 7 tablet (9th gen)

I attempted to force uninstall in ADB, but failed:  $ adb shell pm uninstall -k org.openintents.filemanager $ adb shell pm list packages -f | grep -i manager package:/system/app/FileManager.apk=org.openintents.filemanager   What went wrong here? What can I do?  I used the internal application manager and there isn't an option to delete it.


I am running Debian kFreeBSD wheezy. Accidentally I mounted my zfs pool directly into /mnt. When I try to unmount I get an error:  zfs unmount myzfspool cannot unmount '/mnt': Device or resource busy   How could I fix that?

When running umount /path I get:  umount: /path: device is busy.   The filesystem is huge, so lsof +D /path is not a realistic option.  lsof /path, lsof +f -- /path, and fuser /path all return nothing. fuser -v /path gives:                    USER        PID ACCESS COMMAND /path:            root     kernel mount /path   which is normal for all unused mounted file systems.  umount -l and umount -f is not good enough for my situation.  How do I figure out why the kernel thinks this filesystem is busy?


Basically, I have created a webapp - which should restrict access to users who are not logged in to the system.  The system is utilising a "user" object to persist session state between the client and the server, this effectively serves as the cookie.  The urls /index, /login, /register  can be accessed by all users visiting the webapp, regardless if they are registered, or logged in.  However, anything outside of this url boundary should redirect the user to the registration page.  In order to achieve this, I've been using springs HandlerInterceptorAdapter - and implementing some basic checking in the preHandle(). However - everything I've come up with is getting caught up in a redirect loop.  Any and all suggestions on how to resolve this are most welcome and appreciated. Any advice, articles or examples on where I can expand my knowledge of this use case are most appreciated. Comments on if and why my approach is flawed, and what best practices are I am keen to hear.  Keep in mind id rather not go down the spring security route just yet - trying to keep this as simple as possible.  @Override public boolean preHandle(HttpServletRequest request,                          HttpServletResponse response,                          Object handler) throws Exception {      HttpSession session = request.getSession();     User user;      try {         user = (User) request.getAttribute("user");     } catch (Exception e) {         e.toString();         return true;     }       if (user == null && request.getPathInfo() != "/login"       || user == null && request.getPathInfo() != "/register"      || user == null && request.getPathInfo() == "/index") {          response.sendRedirect("register");         return true;     } else {         return true;     } }

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


when wanting to download third-party software like wire shark or yubico application like personalization tool do I have to install via command line or is it automatically installed like in windows 10?

How can I install applications like Google Chrome on Ubuntu?  Are there any commands to install an application?    Index of answers:


Let $(e_k)$ be any orthonormal sequence in an inner product space $X$. Show that for any $x,y \in X$ $$\sum_{k=1}^\infty|\left<x,e_k\right>\left<y,e_k\right>|\le \|x\|\|y\|.$$   If $x=y$, then the proof becomes trivial, as then the result follows directly from  $$\sum_{k=1}^\infty|\left<x,e_k\right>|^2\le \|x\|^2.$$  Now suppose that $x \neq y$, then \begin{align}\sum_{k=1}^\infty |\left<x,e_k\right>\left<y,e_k\right>| &= \sum_{k=1}^\infty \left|\left<\left<x,e_k\right>y,e_k\right>\right|\end{align} But I have no idea where to continue from here. Can anyone please help point me in the right direction?

Let $V$ be a real inner product space, and let $v_1,v_2, \dots ,v_k$ be an orthonormal set of vectors. How do you prove that  $$\sum_{i=1}^k | \langle x,v_i \rangle \langle y,v_i\rangle| \leq \|x\|\cdot\|y\|?$$  When does the equality hold?  I've been trying to do this with the Bessel and Cauchy-Schwarz inequalities, but I can't make it work yet. Any help would be greatly appreciated.


When loading more than one photo in Affinity I get 1/4 of one on top of another photo. I have to stop Affinity and then quit Affinity to load another photo. Is there a way I can load more than one photo and select which one I want to work on?  Mac 10.13.2

I deal with hundreds if not thousands of images a day.  I use Apple's Aperture program because i can edit many images at a time, and copy metadata from one image to the next.  Has anyone used the new Affinity program for Mac yet, and if so is it like Aperture, or can you only deal with one image at a time?


My question is : is the following reasoning correct ?  Let $X$ and $Y$ be two Banach spaces and let $T:X\rightarrow Y$ a bounded surjective operator. Then $T^{\ast }$ $:Y^{\ast }\rightarrow X^{\ast }$ is a bounded below operator and hence it has a left inverse $R^{\ast }$ $:Y^{\ast }\rightarrow X^{\ast }$, that is $R^{\ast }T^{\ast }=Id_{Y^{\ast }}$ then $% TR=Id_{X}$ and hence $T$ has a right inverse.  Or must $X$ and $Y$ be reflexive to do like ?  Thank you !

Could someone give a simple example of surjective (not bijective) bounded operator in Banach spaces without bounded right-inverse?


I would like to change the color of one object in the shapefile. I have done it with every object of interest and it worked so far. But this one I can’t find by name in the properties. Is it possible to click on that shapefile with the “information button” and go directly to the properties where I can change the color? So far I couldn’t figure it out.   I am using the QGIS 2.12.3 - Lyon Version.

The Identify Results window does not appear when using the identify feature tool  in QGIS 2.4. I guess there's a check box somewhere I need to check/uncheck, but the settings of the tool changed compared to the previous version (see attached printscreen).


I am having a hard time with this problem: I tried by using the sandwich theorem but I failed. $\lim\limits_{n\to\infty} \dfrac{n^b}{a^n}= 0\;,\;$ when $\;a > 1,\; b > 0\;.$ Could anyone please help me?

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


Based on a result  and in conjunction with methods I've observed on MSE I was able to show that:  \begin{equation}  \int_0^\infty \frac{ \ln(t)}{t^n + 1}\:dt = -\frac{\pi^2}{n^2} \operatorname{cosec}\left(\frac{\pi}{n} \right)\cot\left(\frac{\pi}{n}\right) \end{equation}  This is achieved through a simple use of Feynman's Trick. Here we  consider the case when $x \rightarrow \infty$ and $a = 1$: \begin{equation} \int_0^\infty \frac{t^k}{\left(t^n + 1\right)^m}\:dt = \frac{1}{n} B\left(m - \frac{k + 1}{n}, \frac{k + 1}{n}\right)  \end{equation} We see that: \begin{align} \frac{d}{dk}\left[ \int_0^\infty \frac{t^k}{\left(t^n + 1\right)^m}\:dt \right]&= \frac{d}{dk}\left[\frac{1}{n}B\left(m - \frac{k + 1}{n}, \frac{k + 1}{n} \right)\right] \\  \int_0^\infty \frac{t^k \ln(t)}{\left(t^n + 1\right)^m}\:dt &= \frac{1}{n^2}B\left(m - \frac{k + 1}{n}, \frac{k + 1}{n} \right)\left[\psi^{(0)}\left(\frac{k + 1}{n}\right) - \psi^{(0)}\left(m - \frac{k + 1}{n}\right) \right] \end{align}  Thus,  \begin{equation} \lim_{k \rightarrow 0} \int_0^\infty \frac{t^k \ln(t)}{\left(t^n + 1\right)^m}\:dt = \lim_{k \rightarrow 0}\frac{1}{n^2}B\left(m - \frac{k + 1}{n}, \frac{k + 1}{n} \right)\left[\psi^{(0)}\left(\frac{k + 1}{n}\right) - \psi^{(0)}\left(m - \frac{k + 1}{n}\right) \right] \end{equation}  And finally:  \begin{equation}  \int_0^\infty \frac{ \ln(t)}{\left(t^n + 1\right)^m}\:dt = \frac{1}{n^2}B\left(m - \frac{1}{n}, \frac{1}{n} \right)\left[\psi^{(0)}\left(\frac{1}{n}\right) - \psi^{(0)}\left(m - \frac{1}{n}\right) \right] \end{equation}  Note: In the case where $m = 1$ we arrive:  \begin{align}  \int_0^\infty \frac{ \ln(t)}{\left(t^n + 1\right)^1}\:dt &= \frac{1}{n^2}B\left(1 - \frac{1}{n}, \frac{1}{n} \right)\left[\psi^{(0)}\left(\frac{1}{n}\right) - \psi^{(0)}\left(1 - \frac{1}{n}\right) \right] \\ &= \frac{1}{n^2} \Gamma\left(\frac{1}{n} \right)\Gamma\left(1 - \frac{1}{n} \right) \cdot -\pi\cot\left(\frac{\pi}{n}\right) \\ &= \frac{1}{n^2} \frac{\pi}{\sin\left(\frac{\pi}{n}\right)}\cdot -\pi\cot\left(\frac{\pi}{n}\right) \end{align}  Thus: \begin{equation}  \int_0^\infty \frac{ \ln(t)}{t^n + 1}\:dt = -\frac{\pi^2}{n^2} \operatorname{cosec}\left(\frac{\pi}{n} \right)\cot\left(\frac{\pi}{n}\right) \end{equation}  Now for the final line I employed  formula:  \begin{equation} \Gamma\left(\frac{1}{n} \right)\Gamma\left(1 - \frac{1}{n} \right) = \frac{\pi}{\sin\left(\frac{\pi}{n}\right)} \end{equation}   The result for the  expression: \begin{equation} \psi^{(0)}\left(\frac{1}{n}\right) - \psi^{(0)}\left(1 - \frac{1}{n}\right) = -\pi\cot\left(\frac{\pi}{n}\right) \end{equation} This was found simply from . I did not derive this myself and this is where my question is founded in. I have no idea how to approach this identity. Does anyone have any starting points? and/or solutions?

How does one prove the polygamma reflection formula:  $$\psi^{(n)}(1-z)+(-1)^{n+1}\psi^{(n)}(z)=(-1)^n \pi \frac{d^n}{d z^n} \cot \pi z $$  Do we have to invoke the power of contour integration and kernels? I searched the web but the proof was to be found nowhere.


Suppose   $E=\{f\in C^1[0,1]$:  $f(0)=0$,$f(1)=1\}$.   Find the maximal $u\in \mathbb{R}$,such that forall $f\in E$,   \begin{align*} \int_0^1|f'(x)-f(x)|dx \geqslant  u. \end{align*}   I can prove that $u\geqslant \frac1e$,since \begin{align*} \frac1e=e^{-x}f(x)\Big|_0^1=\int_0^1e^{-x}(f'(x)-f(x))dx\leqslant \int_0^1|f'(x)-f(x)|dx . \end{align*} But I don't know how to find the  maximal $u$.

Let $C$ be the class of all real-valued continuously differentiable functions $f$ on the interval $[0,1]$ with $f(0)=0$ and $f(1)=1$. How to show that $$\inf_{f\in C}\int_0^1|f'(x)-f(x)|dx=\frac{1}{e}?$$  I have been able to show that $1/e$ is a lower bound. Indeed, $$\begin{align*} \int_0^1|f'(x)-f(x)|dx &= \int_0^1|f'(x)e^{-x}-f(x)e^{-x}|e^xdx \\ &\geq \int_0^1\left(f'(x)e^{-x}-f(x)e^{-x}\right) dx \\ &= \int_0^1 \frac{d\left(f(x)e^{-x}\right)}{dx}dx  \\ &= f(1)e^{-1}-f(0)e^{0}\\ &=\frac{1}{e}. \end{align*}$$ But how to show this is the infimum? Is there a function $f\in C$ such that we get $\int_0^1|f'(x)-f(x)|dx=1/e$?


Scanner class doesn't work how I expected.  Scanner in = new Scanner(System.in); // input: total  String str = in.nextLine();          // total System.out.println(str);             // total System.out.println(str == "total");  // false System.out.println(str != "total");  // true   I expected line 5 being true, but the above code is what i got.  How should I do for (str == "total") becomes true?

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


I borrowed a Windows 7 disk from my friend and I thought it was 32bit but it turned out to be 64bit and I only have 2GB of RAM. Since I have some stuff that I would rather not install again because it took a long time, is there a way to make the 64bit Windows a 32bit Windows without reinstalling Windows?

Is it possible to convert 64 bit Windows 7 to 32 bit Windows 7 keeping the settings and installed software where they were ?  I am not interested in virtual machine based options.


In Game of Thrones S07E04, the conversation between Cersei and the Iron Bank representative reveals that she plans to repay the crown's debt to the Iron Bank with gold recovered in the conquest of Highgarden.  The Iron Bank representative is impressed and conditionally agrees to extend further credit for Cersei's wars upon the repayment of the prior loans.  However, Jaime's army marching the gold home to King's Landing is attacked by Daenarys (with her dragons) and the Dothraki.  I think it is made abundantly clear that Jaime loses this battle at the end of S07E04, and Daenarys's forces win control of the field.  Jaime's wagons are burned and his armies are decimated.  At the beginning of S07E05, the Dothraki are seen leisurely picking over the battlefield for good steel while Jaime is off getting half-drowned and waking up alone on the river bank with Ser Bron of the Blackwater, his highborn commanders off being executed by dragonfire.  Yet, in the very next scene we see Jaime explaining his defeat to Cersei, and she still seems confident that the Iron Bank is going supply her with gold for making war.  Why?  Is Daenarys allergic to gold?  Have I missed something?

In season 7 Cersei attacks      House Tyrell and gets all their gold,   in order to pay the debts to the Iron Bank and then ask their help to hire some mercenaries. But before the gold is back in King's Landing      they're attacked by the Dothraki and a dragon, and (apparently) lose the gold.   It made me think that the support from the Iron Bank was lost too. But, in the last episode, it appears they still have the support of the Bank to hire the mercenaries.  So the question:       Did she recover the gold after the defeat or does the Iron Bank help her without having recovered the gold?


I'm not sure if those two words are completely synonymous in all context and which connotation they have.  Here are some example sentences where I would use them synchronously, but I'm not sure if this is correct:   Answering this question is [easy / simple]. His live is [easy / simple].   I think there is a difference in   I can simply / easily do it: The first sounds a bit more like somebody is resignating, e.g. somebody else did not do the job he was supposed to do. The second emphasizes that the task is not difficult.   And here is the Google ngram:

Are those two words equivalent or is there a difference? When would I say something is easy rather than simple, or vice versa?


I create a directory called bob@example.com/    I wanted to use this email address as the directory name - I know - not a good idea for many reasons - but lets assume this is a very temporary directory that I delete seconds later :)  I give the command  mkdir bob@example.com   However when I check the directory I see it actually created it with quotes around it.  ... 'bob@example.com` ...   I then found this is due to the @  What are the rules for special characters in directory names and how does the system decide to quote them

I just noticed that on one of my machines (running Debian Sid) whenever I type ls any file name with spaces has single quotes surrounding it. I immediately checked my aliases, only to find them intact. wyatt@debian630:~/testdir$ ls 'test 1.txt'  test1.txt wyatt@debian630:~/testdir$ alias alias ls='ls --color=auto' alias wget='wget --content-disposition' wyatt@debian630:~/testdir$   Another test, with files containing single quotes in their names (also answering a request by jimmij): wyatt@debian630:~/testdir$ ls 'test 1.txt'  test1.txt  'thishasasinglequotehere'\''.txt' wyatt@debian630:~/testdir$ touch "'test 1.txt'" wyatt@debian630:~/testdir$ ls ''\''test 1.txt'\'''  test1.txt 'test 1.txt'          'thishasasinglequotehere'\''.txt'   update with new coreutils-8.26 output (which is admittedly much less confusing, but still irritating to have by default). Thanks to Pádraig Brady for this printout: $ ls "'test 1.txt'"   test1.txt 'test 1.txt'    "thishasasinglequotehere'.txt"  $ ls -N 'test 1.txt'  test1.txt test 1.txt    thishasasinglequotehere'.txt  Why is this happening? How do I stop it properly? To be clear, I myself set ls to automatically color output. It just never put quotes around things before. I'm running bash and coreutils 8.25. Any way to fix this without a recompile? EDIT: Appears the coreutils developers  to break with the convention and make this the global default.  UPDATE - October 2017 - Debian Sid has re-enabled the shell escape quoting by default.  And at the bottom of the reply chain to the previous bug report, "the change was intentional and will remain."  I thought this had already been settled, but apparently it was just reverted so that the "stable" Debian branch could keep its "feature freeze" while getting the other fixes, etc. from the newer version. So that's a shame (in my opinion). UPDATE: April 2019: Just found a  that was caused by this change to ls. When you're confusing developers and generating false bug reports, I think it might be time to re-evaluate your changes. Update: Android toybox ls is now doing something similar to this but with backslashes instead of quotes. Using the -q option makes spaces render as 'question mark characters' (I have not checked what they are, since they're obviously not spaces), so the only fix I have found so far without rooting the device in question is to add this to a script and source it when launching a shell. This function makes ls use columns if in a terminal and otherwise print one-per-line, while tricking ls into printing spaces verbatim because it's running through a pipe. ls() {     # only way I can stop ls from escaping with backslashes     if [ -t 1 ]; then         /system/bin/ls -C $@ |cat     else         /system/bin/ls $@ |cat     fi }


Our specific use case requires that we alert the user only when they're trying to close a window or tab in a browser, but not on other triggers of this event such as clicking on an href _blank for urls that open in new window. Is this possible with raw JS either via this event handler or some other? Thanks

I need to warn users about unsaved changes before they leave a page (a pretty common problem). window.onbeforeunload = handler  This works but it raises a default dialog with an irritating standard message that wraps my own text. I need to either completely replace the standard message, so my text is clear, or (even better) replace the entire dialog with a modal dialog using jQuery. So far I have failed and I haven't found anyone else who seems to have an answer. Is it even possible? Javascript in my page: <script type="text/javascript">        window.onbeforeunload = closeIt; </script>  The closeIt() function: function closeIt() {   if (changes == "true" || files == "true")   {       return "Here you can append a custom message to the default dialog.";   } }  Using jQuery and jqModal I have tried this kind of thing (using a custom confirm dialog): $(window).beforeunload(function () {     confirm('new message: ' + this.href + ' !', this.href);     return false; });  which also doesn't work - I cannot seem to bind to the beforeunload event.


Things change over time. The latest question I found on this topic was from 2014 and appears to refer to 14.04. We are running 18.04 server. What is the current way to setup swap encryption? Is the preferred process still the same?  The requirements are, on boot clear swap, create a key and enable encryption of swap. On shutdown/reboot, forget key.  The documentation I am being pointed to is for desktop/laptops and is focused on hibernation and forces you to provide a password on boot and so is not a suitable option for servers.  In the comments below I have had suggested:   ecryptfs-setup-swap cryptsetup   If we add other currently unknown options to this list, which is the preferred method? I expect this server to last ~5 years. Is one better than another? How?

When I installed Ubuntu, I setup an encrypted home partition. Now I have come to an issue where I am running out of memory because I haven't setup swap. How can I setup an encrypted swap file?  A couple of times while booting I've seen some reference to cryptswap. I've also got these lines contained in /etc/fstab  # swap was on /dev/sda6 during installation #UUID=1ba8a53b-1842-4de7-8e38-2d6c79f3a1ab none            swap    sw              0       0 /dev/mapper/cryptswap1 none swap sw 0 0


How does the mean influence PCA? What happens if I use PCA on data with a mean $\ne0$?

I keep reading about instances where we center the data (e.g., with regularization or PCA) in order to remove the intercept (as mentioned in ). I know it's simple, but I'm having a hard time intuitively understanding this. Could someone provide the intuition or a reference I can read?


If electrons move from the negative side to the positive side in a battery (thus creating electricity when they flow), why does the same circuit with two separate batteries not create electricity?   As you can see in the diagram, electrons should be moving from A to B because the wire is connected from A - side (high pressure) to B + side (low pressure). Why is there no electron flow?

Imagine a battery with the positive terminal connected to ground.  The positive side has a high eletrical potential, ground obviously has a lower electric potential.  Electricity wants to seek a lower potential, and there's no significant resistance between the terminal and the ground.  Shouldn't electricity flow?  I know it doesn't but I don't understand why.  I know you have to close the loop, but why is this necessary?


I just setup virtual machines on one hardware with Vagrant. I want to use a Puppet to configure them and next try to setup OpenStack. I am not sure If I am understanding how this should look at the end. Is it possible to have below architecture with OpenStack after all where I will run one Virtual Machine with Linux?  ------------------------------- |          VM with OS         | ------------------------------- | NOVA    | NOVA    | NOVA    | ------------------------------- |          OpenStack          | ------------------------------- |  Node   | Node    | Node    | -------------------------------   More details:  In my environment Nodes are just virtual machines, but my question concerns separate Hardware nodes. If we imagine this Nodes(Novas) are placed on a separate machines (e.g. every has 4 cores) can I run one Virtual Machine across many OpenStack Nodes? Is it possible to aggregate the computation power of OpenStack in one virtual distributed operating system?

We are studying implementing some virtualized servers here, but we don't know what will be better suitable for us. Some folks are saying better have two huge servers, and others are saying have like a ten middle-end servers.  We have a legacy Visual Foxpro application, which nowadays run on Dual Xeon E5405 @ 2GHz and 16Gb of RAM. The currently server its getting too slow due the number of active users and process running on it. Virtualizing this server will give us the benefit of an faster disaster recovery.  So the question is, having like ten physical servers running at 1.7GHz and 4Gb of RAM, we could virtualize one server into 4 machines, and have one virtualized server running at 6.8GHz and 16Gb of memory? If yes, there is some how if one machine stops, automatically manage this virtual machine to another one, and execute the appropriate maintenance on it, and later back to it again?


The question is clear from title. Can I run Android app on Ubuntu directly like 🍷 (wine).   If Ubuntu and Android both have Linux kernel then why can't we run Android app directly or with help of any other little software?

Is it possible to run Android apps on Ubuntu? And I don't mean inside an emulator, but natively, as you would with any other application installed using the Ubuntu Software Center.


Does someone have an example of three ideals such that no one is contained in another, yet their union is an ideal?

Prime Avoidance Theorem says:     Let $ P_1, P_2,\dots, P_n $ be prime ideals in a commutative ring   $R$ and let $I$ be an ideal of $R$ such that $ I \subseteq P_1 \cup P_2 \cup \cdots \cup P_n$. Then $ I \subseteq P_k $ for some $k\in \{1,2,\dots,n\}$.   Is true if replace prime ideals by primary ideals?


How can I find an old command I ran in my terminal?  I used an appengine command and wish to just find it in my local command history without researching it online again.

Other than viewing the history, is there a way to filter my history?  Say I want to search for a command that started with "ssh"?


I am updating the data in database from php and Getting Up Error:Query was empty with query. I badly need help. Thanks in Advance  <?php $dbhost = 'localhost'; $dbuser = 'root'; $myDBname = 'jsv'; $conn = mysql_connect("localhost", "root"); mysql_select_db('jsv'); if(isset($_POST['update'])) { $nam = $_POST['namnid']; $mandag = $_POST['mandagid']; $tisdag = $_POST['tisdagid']; $torsdag = $_POST['torsdagid']; $fredag = $_POST['fredagid'];  $sql = mysql_query("INSERT INTO jsv(CA_ID,Name,Address,Amount)  VALUES ('$mandag', '$tisdag', '$torsdag', '$fredag') WHERE Setup_Box_No = '$nam'", $conn); if(!$sql ) {   die('Could not update data: ' . mysql_error()); } echo "Updated data successfully\n";  }  mysql_close($conn); ?>

What's wrong with this query: INSERT INTO Users( weight, desiredWeight ) VALUES ( 160, 145 ) WHERE id = 1;  It works without the WHERE clause. I've seemed to have forgot my SQL.


I'm new to programming and while working on the Head First Java book I wanted to make a simple program, but there are some points I can't do. What I want the program to do is keep an integer number between 0 and 100 randomly and the user tries to find it. If the user finds the number, congratulations will appear on the screen. If not, it will ask for a new prediction. The code I wrote is below: package Intro; import java.util.Scanner;  public class GuessingGame {     public static void main(String[] args) {          Scanner input = new Scanner(System.in);          System.out.println("Please enter a number: ");          int prediction = input.nextInt();          int number = (int) (Math.random());          if (number==prediction) {              System.out.println("Congratulations!");         }           else {              System.out.println("Wrong answer! Try a new number: ");          }            } }  The point I stuck is that I can't make the randomly stored number integer and a number between 0 and 100. Another point is that if the answer is wrong, the program does not want a new prediction.

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


Let $f:\mathbb{C}\to\mathbb{C}$ be an entire function.  Let $n\in\mathbb{N}$ and suppose that  $$\forall w\in\mathbb{C}:\#\{z\in\mathbb{C}:f(z)=w\}\leq n$$  In words, every complex value is attained by $f$ in at most $n$ different places.  Prove that $f$ is a polynomial of degree at most $n$.

Let $n\in\mathbf{N}$ be fixed, and $f$ entire and $|f^{-1}(\left\lbrace w\right\rbrace)|\leq n$ for every $w\in\mathbf{C}$. Then $f$ is a polynomial of degree at most $n$.    I try to prove this statement, and I think one can prove it as follows: consider $f(1/z)$. $0$ cannot be an essential singularity of $f(1/z)$, for the big Picard theorem would imply that on any neighborhood of $0$ $f(1/z)$ takes on all possible complex values (with at most one exception) infinitely often, but this is contrary to $|f^{-1}(\left\lbrace w\right\rbrace)|\leq n$. Then $f(1/z)$ has a pole of order $k$ say, and since $f$ is holomorphic it is a polynomial of degree $k$ (for its principal part vanishes). By the fundamental theorem of algebra, $k\leq n$.      Is it possible here to avoid using Picard's theorem?


Given positive integers a and b such that $a\mid b^2, \:b^2\mid a^3, \:a^3\mid b^4,\: b^4\mid a^5$..., prove $a=b.$   I was able to show that a and b have the same primes in their factorizations, but I'm not sure how to show that the exponents on these primes are equivalent for all primes in their factorization. I tried contradiction but got stuck.

Let $a,b$ be positive integers such that $a\mid b^2 , b^2\mid a^3 , a^3\mid b^4 \ldots$ that is $a^{2n-1}\mid b^{2n} ; b^{2n}\mid a^{2n+1} , \forall n \in \mathbb Z^+$ , then is it true that $a=b$ ?


I am looking for a way to decrypt aes that was encrypted earlier in mysql and then migrated to postgresql. In mysql I used standard aes_encrypt with block encryption mode aes-128-ecb, but I can't seem to be able to decrypt that in postgresql.  I am currently trying my luck with the decrypt function from pgcrypto module of postgresql 12, but I cannot make it to use 128-bit key length. The documentation listed aes-128 as possible, but didn't say how to enable it.  I was trying CAST(decrypt(cc_data, '...key here...','aes-ecb') AS VARCHAR but this shows wrong result. Choosing 'aes-128-ecb' results in 'No such cipher algorithm' error.

I have this MySQL query using  that is the following:  SELECT *  FROM data_tbl WHERE AES_DECRYPT(data_point,'aBcDeF')='data_1';   I've figured out as much that the equivalent in Postgres 11 is  (F.25.4. Raw Encryption Functions) and the query would look something like this:  SELECT *  FROM data_tbl AND decrypt(data_point,'aBcDeF','aes')='data_1';   At least, the documentation for both leads me to believe that these are equivalent.  The data was dumped from MySQL and imported into PostgreSQL.   The data-point field in MySQL is type varbinary(255) and the values all show BLOB in MySQL Workbench.  The data_point field in Postgres is type bytea and the values all show [binary data] in pgAdmin.    Whether those data types are equivalent, I admit, I'm not sure.  The MySQL query works and finds a record based on he criteria. The PostgreSQL does not, although the record is in there. So it seems like one of three things:   The data types (varbinary(255) vs bytea) are not equivalent The data does not match (BLOB vs [binary data]) are not equivalent The functions (AES_DECRYPT vs decrypt()) are not equivalent   I did try to decrypt the value in PostgreSQL just to see what it is in a readable format by first trying:  SELECT decrypt(data_point, 'aBcDeF', 'aes')  FROM data_tbl;   But that just returned [binary data] for all the rows.  Then I came across  to use convert_from as in:  SELECT convert_from(decrypt(data_point, 'aBcDeF', 'aes'), 'SQL_ASCII') FROM data_tbl;   However, I just get this error:  ERROR:  invalid byte sequence for encoding "UTF8": 0xcf 0xf5 SQL state: 22021   So at this point I'm stumped as to how to resolve the primary issue. The primary issue being doing the equivalent of AES_DECRYPT but in PostgreSQL 11. The last error message isn't so much an issue, but it is likely related to decrypt() not returning the same results.  Any suggestions?


For parallel spins, our instructor told us that it is because of pauli exclusion principle. Here is my doubt : if total spin is 1. That means spin part of wavefunction is symmetric, but if the spatial part of the wave function is anti-symmetric , the overall state will be anti-symmetric, which is good. How does then pauli exclusion principle rule out this possibility? Please, clarify.

It is known that there are no diproton or dineutron nuclei.  Does this mean that two protons or neutrons are not actually attracted to each other? Even if the attraction was weak, wouldn't it cause bound states anyway?  Related:


How can I know if an alias I make (in .bash_aliases) is not replacing an actual command by same name? I don't want to do such things by accident.  (I looked in "Questions that may already have your answer" and "Similar Questions" but did not see matches)  I'm asking because I feel there is no warning given by the system (Ubuntu 13.10).

Suppose I have an alias in the bash shell. Is there a simple command to print out what command the alias will run?


How to prove that the determinant of the product of matrices is equal to product of their respective determinants ?.ie,     $$ |A.B|=|A|.|B| $$   where $A,B$ are square matrices of the same order.   I have no clue of where to start, I just know the following  $$ |A|I=A(adj A)=(adj A)A $$ Note: I have checked a similar problem at  which gives a combinatorial proof of the statement which is kinda cumbersome by the use of Combinatorics in a matrix problem. So I hope its worth asking for an alternative proof using only the properties of matrices.

One of definitions of the determinant is:  $\det ({\mathbf C})       =\sum_{\lambda \in S_n} ({\operatorname {sgn} ({\lambda}) \prod_{k=1}^n C_{k \lambda ({k})}})$  I want to prove from this that  $\det \left({\mathbf {AB}}\right) = \det({\mathbf A})\det({\mathbf B})$  What I have so far:  $(AB)_{k\lambda ({k})} = \sum_{j=1}^n A_{kj}B_{j\lambda(k)}$  so we have for the determinant of $\mathbf {AB}$  $\det ({\mathbf {AB}})       =\sum_{\lambda \in S_n} ({\operatorname {sgn} ({\lambda}) \prod_{k=1}^n \sum_{j=1}^n A_{kj}B_{j\lambda(k)}})$  Now I'm not sure how to denote this, but the product of the sum I think is the sum over all combinations of n terms, each ranging from 1 to n, so I'll denote this set of all combinations $C_n(n)$ for n terms each ranging from 1 to n, analogous to the permutation set, but all combinations instead of permutations.  then I get  $\det ({\mathbf {AB}})       =\sum_{\lambda \in S_n} ({\operatorname {sgn} ({\lambda}) \sum_{\gamma \in C_n(n)} \prod_{k=1}^n A_{k\gamma(k)}B_{\gamma(k)\lambda(k)}} )$  then I can at least seperate the product:  $\det ({\mathbf {AB}})       =\sum_{\lambda \in S_n} ({\operatorname {sgn} ({\lambda}) \sum_{\gamma \in C_n(n)} \prod_{k=1}^n A_{k\gamma(k)} \prod_{r=1}^n B_{\gamma(r)\lambda(r)}} )$  I changed the k to an r in one product because it's a dummy variable so I think it doesn't matter, I don't really know if this thing is helpful but this is my attempt at a solution so far.  Thanks to anyone who helps!


I tried to install Dropbox, now I am trying to install Sublime Edit Why deb files don't install itself??? I want the latest build and not some outdated version from Software Center that is few years old and uploaded by some anonymous user

I tried to install some .deb files in Ubuntu 20.04 from GitHub and other internet sources, but when I open it with Software Install it gives me  problem (Failed to install file: not supported). The only way for me to install them is to go to the downloaded file and do sudo dpkg -i file.deb. Can anyone help? I don't know what to do and I don't want to use the terminal every time. Any help would be appreciated, thanks EDIT: that's NOT a problem with .deb in Ubuntu, it is a problem with Software install. I can install every .deb through the terminal but not with Software install, and Ubuntu suggests to install .deb with Software install. That's not a dependencies problem or anything similar, that's an issue with installing .deb WITH Software install and I would like to know how I can fix Software installer


I have searched a bit without finding a solution. I want to change the biblatex style (citation and bibliography), regarding the "number" field in periodics and others.  I would like to change this :     Zerrouk Yamina, « Gestion des sites et sols pollués et fiucie », JCP    9 (28 fév. 2014), p. 47.   Into this :     Zerrouk Yamina, « Gestion des sites et sols pollués et fiucie », JCP ,   n° 9 (28 fév. 2014), p. 47.   I already have bbx and cbx files, so I would like to add a potential change in those files. I didn't find anything in the documentation...  I use lualatex.  Thanks a lot for any help ! :)

So the current product looks like this:     Gillies, A. (1933), “Herder and the Preparation of Goethe’s Idea of World Literature”,   in: Publications of the English Goethe Society 9 (2), pp. 46–67.   Due to guidelines I must produce this though:     Gillies, A. (1933), “Herder and the Preparation of Goethe’s Idea of World Literature”,   in: Publications of the English Goethe Society, vol. 9, iss. 2, pp. 46–67.   ("Volume" and "issue" would be fine as well.)  Here is an MWE:  \documentclass[ 12pt, a4paper ] {scrreprt}  \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{lmodern} %\usepackage[english]{babel}  \usepackage{hyperref} \usepackage[ language=auto, style=authoryear, backend=bibtex, hyperref=true, isbn=false, doi=false, citereset=chapter, maxcitenames=3, dashed=false, sorting=nyt, natbib=true, %faking natbib-commands firstinits=true, terseinits=false maxbibnames=99, %autopunct=true, uniquename=init ]{biblatex} \usepackage{xpatch}  \renewcommand*{\newunitpunct}{\addcomma\space}   \begin{filecontents*}{lit.bib}  @Article{gillies,   hyphenation     = {british},   author      = {Gillies, Alexander},   title       = {Herder and the Preparation of Goethe's Idea of World Literature},   journaltitle    = {Publications of the English Goethe Society},   volume      = {9},     issue = {2},   date        = {1933},   pages       = {46--67},   annotation      = {An \texttt{article} entry with a \texttt{series} and a \texttt{volume} field.             Note that format of the \texttt{series} field in the database file} } \end{filecontents*}  \addbibresource{lit.bib}  \begin{document} \chapter{First Chapter} \begin{itemize}     \item For the case of multiple editors, these are just some words.\footcite[See][p. xi]{gillies}. \end{itemize} \printbibliography \end{document}


In water the speed of light changes to $2.25 \cdot 10^8m/s$.   Can a electron travel faster/travel at the same speed   in water. I don't see any violation of SR. So   shouldn't it  be possible for an electron to travel at say $2.5 \cdot 10^8m/s $. Water is just an example.In other mediums like hydrogen electrons in excited states should travel at higher speeds than that of light in the same medium.

While the speed of light in vacuum is a universal constant ($c$), the speed at which light propagates in other materials/mediums may be less than $c$. This is obviously suggested by the fact that different materials (especially in the case of transparent ones) have a particular .  But surely, matter or even photons can be accelerated beyond this speed in a medium?  If so, what are the effects?


I have installed ffmpeg by following   Now, ffmpeg works if I cd to bin and execute it with ./ffmpeg  I wonder if I could execute ffmpeg just by typing ffmpeg in a terminal from anywhere.

How do I add a directory to the $PATH in Ubuntu and make the changes permanent?


Please bear with me, memories are vague. I'm looking for the name of a short scifi story, by a fairly prominent author IIRC, where a person was evolving "pet artificial life" in their basement. Written circa 2000, I think.  As the story proceeded the life got increasingly more complex. It started off simple but became gradually more well-defined and intelligent, resembling organisms, and later evolved a civilization. The evolution kept speeding up until one day the person came back to find his "artificial creatures" managed to break out of the confinement he imposed on them. The civilization basically became smarter than humans, and escaped ?into another dimension? via some new physics it invented, in a singularity event.  I'm not 100% sure, but I think the life was digital = evolving in a computer. But I may be wrong about that. In any case, the life was super tiny / not visible, so if not digital, maybe microscopic / nanotech or something.  Fairly short, perhaps 20 pages in total.  What I remember from the story is that the person tried to set up restrictions for what his creation could do without harming them, making the constraints ever more sophisticated as the life became smarter and smarter. But in the end, they managed to escape anyway (they vanished, basically, without harming the person or anyone else).  EDIT: I just went through short stories of Ted Chiang, because I thought it might have been him. But no luck there :(

I read this a few years ago online: a man creates some kind of simulated world using a quantum computer with creatures that end up evolving to look 'crab-like'. He's able to fast-forward the simulation; after fast-forwarding to where they're of human-level intelligence and grieving over their dead, he is emotionally unable to let them continue dying. That generation lives forever and (I believe) he stops them from being able to reproduce, so the population is entirely stagnant immortals. At some point he establishes contact with a crab-being, but only one.  Does anyone else remember reading it, what it was called, or what the website it was hosted on could have been?


We're running RHEL6, which only officially supports glibc 2.12.  A user is requesting that we install a newer version.  I grabbed 2.18 from  and had no trouble running configure/make.  However when I attempt a small program to test it, I don't get the desired result:  test.c  #include <stdio.h> #include </scratch/new-glibc-testing/include/gnu/libc-version.h> int main (void) { puts (gnu_get_libc_version ()); return 0; }   I then compile and run with:  gcc test.c ./a.out   And the output I get is:  2.12   when I was hoping to get:  2.18   I also tried:  gcc -I/scratch/new-glibc-testing/include test.c   and changed the define line to:  #include <gnu/libc-version.h>   which compiles, but gives the same result (2.12).  I tried also using -nostdlib, ex:  gcc -nostdlib -I/scratch/new-glibc-testing test.c   This, however, throws errors:  /usr/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400144 /tmp/cc6x03Do.o: In function `main': test.c:(.text+0x5): undefined reference to `gnu_get_libc_version' test.c:(.text+0xd): undefined reference to `puts' collect2: ld returned 1 exit status   gcc --version results in: gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-4)

Time and time again I see questions such as these:       And these are the types of solutions we're typically pushing:        Is this really the best we can do? Aren't there binary builds of GLIBC that we can simply unzip into a directory such as /opt/myglibc, and set the $LD_LIBRARY_PATH or whatever and run whatever application we want, without issues?   An application, such as the newer builds of Chrome (28+) that appear to require GLIBC 2.14?  NOTE: This thread titled:  on tecmint.com is what ultimately got me thinking about this.  References


Question: Suppose $f$ is differentiable in an interval $E \subset R$. Prove that $f'$ is bounded on $E$ if and only if a constant $M$ exists such that $|f(x) − f(y)| \le  M|x − y|$ for all $x, y \in E$. My approach: I'll skip the part about the $\Leftarrow$ direction since it is quite straightforward. Assume that $f'$ is bounded. Set $\phi(t)$ as $f(t)−f(x)/t−x$. Then $$|\lim_{t\to x} \phi(t)| = |f'(x)| \le  M$$ according to the characteristic of boundedness. The next step is the part where I'm unsure whether it is legit. multiply $|t-x|$ on both sides of inequality then it will derive $|f(t) − f(x)| \le M|t − x|$. Is this approach appropriate? Or is there more legitimate way to prove this condition?

This is a very common proof, but there is one point, which many just seem to take for granted.  At one point I'll use the mean value theorem to say  $$ w.l.o.g.\quad  x > y \quad x,y \in (a,b) $$   And from the mean value theorem I get a term like this  $$\frac{f(x)-f(y)}{x-y} = f'(\xi) \leq L $$  But people often conclude $$|f(x)-f(y)| \leq L|x-y|$$  Is that step always true? i.e. is it always true that   $$ x = y \rightarrow |x|=|y| $$


I want to install unity as DE in Ubuntu 18.04.Is it possible.

I recently installed Ubuntu 18.04 and I'm not keen on the desktop environment. I want the desktop env. I used to have in Ubuntu 14.04. How can I get it?  I've attempted to use , but when I try to install the Unity's 7.2.5 version using the command:  apt install unity=7.2.5   it gives me   E: Version '7.2.5' for 'unity' was not found   For sure I need to add a PPA for this, but which one!?


If anything that I have learned from Walter White's character in Breaking Bad, it is his love for lab and chemistry. After leaving Gray Matter, why didn't he continue his research, or decide to start his own business, as he was a genius chemist that anyone has ever seen?  Becoming a school teacher doesn't suit his type and was a waste of his talent. Starting from the very first episode we see that he is poor (before his cancer is diagnosed). Why didn't he think about his family before, leaving them with money etc.?

We are given some explanation as to why Walt quit Gray Matter and thereby forfeited his opportunity to make billions (tl; dw --- personal issues with the co-founders).   But is it ever explained why he is teaching chemistry in a high school? Walt is obviously a talented chemist. I am not familiar with the job market for chemists but it seems that he obviously has better job opportunities (e.g. chemistry professor at any university, research scientist, work at a pharmaceutical lab). The pay is paltry and he doesn't seem to take great pleasure out of teaching high school kids. So why does he teach at a high school?  Quote from :     I am an extremely overqualified high school chemistry teacher. When I   can work, I make $43,700 per year. I have watched all of my colleagues   and friends surpass me in every way imaginable


Hasirama is one of the most OP characters in the Naruto series. No one could match his strength, even Madara, and he had crazy regenerative abilities. Basically, he had no weaknesses. Narutopedia sums it up pretty well:     Hashirama was famed as the strongest shinobi of his era, reputed as a God of Shinobi ... His body was brimming with vitality, granting him considerable regenerative powers that could mend most injuries with no residual effects ... Hashirama was proficient in all five basic nature transformations, along with Yin and Yang Release ... [It goes on and on]   So how did someone like him die in the First Shinobi World War? He alone has the same power as an entire village, and so long as he is careful, no one can even scratch him. And if he gets hurt, he can just heal it and shrug it off. So how could he so carelessly die?

The wiki says that Hashirama died shortly after the creation of Konohagakure.  Do we know how he died?  I mean, he was powerful enough to stand up to Madara, so I feels like it would be no small thing that could kill him.


This 80s children TV series was probably British, but I'm not sure about that.  There were two kids (brother and sister) and a chest in the attic. The chest was a portal to another world. In that world there was a forest and some puppet animals. I remember one of them being a talking python.  It was live action with puppets.

I remember watching this one show when I was a kid in the 80's/early 90's in Canada. It was a live-action show about these two kids and had some puppet/muppet-like characters, but it kind of had a dark/mysterious element to it. I can't remember too much about it except portions of some episodes, but the main characters were kids, and they had some mysterious artifact (kind of like a compass?) that took them to this other world where there were giants and other mysterious beings that we rarely saw. The two kids weren't the only one's going to this place either, they find out kids from all around the world that also had this same artifact (and they all fit together like a round puzzle?). I seem to recall that the giants in this other world were the ones who made the artifacts, and were dying/or in desperate need of the help of the kids.  A couple episodes I remember:   There was one where the leaves were falling, and the world was doomed to end as soon as the last leaf touched the ground, so they're trying to figure out how to prevent all the leaves from falling, but after a long and suspenseful episode (for a kid) the last leaf dramatically falls, but out of no where the main girl catches the leaf and saves the world (it was very exciting for my young self, and I remember being very impressed with the pretty girl for thinking to catch the leaf).     There was another episode where the kids meet these two old guys with long white hair (muppets) sullenly working in a mine/tunnel, they're in tattered old clothes working away with their pick axes or hammers and they are connected to each other at the beard. This long old white beard grows out of one of their faces right into the other's. The kids save the day by cutting the old guy's beard in the middle, freeing them from each other. They celebrate being free from their bonds and excitedly thank the kids, but after the kids leave they continue to work away, this time in much brighter spirits. Seemingly unbeknownst to them though, as they work, their beards slowly and subtly grow back together.   Anyone else remember this show?


I have a c# .NET 3.5 application which retrieves various user properties. Out of them 'TerminalServicesHomeDirectory', 'TerminalServicesHomeDrive' are 2 properties I need to fetch. On the DirectorySearcher, if I add these 2 propertiesToLoad property and do a FindAll(), the SearchResult object does not contain these properties.   I will have to do SearchResult.GetDirectoryEntry() and from the obtained directory entry, when I do InvokeGet, I get the values.  My question is, is there a way I can get value for these properties without having to create directory entries for each SearchResult ?  Is there anything I am missing? Thanks!

I have read the following properties from AD,  TerminalServicesProfilePath TerminalServicesHomeDirectory TerminalServicesHomeDrive   I've tried DirectoryEntry and DirectorySearcher. But they does not include the properties.  I found some example in vbscript and VC to read them. However I failed to make it working in C#. Am I missing some tricky thing?  EDIT: Am I have to run it on "Windows Server" to make it works? Can it be read from win XP?


I am implementing Theta* pathfinding in a tile-based 2D game. A tile is either blocked or unblocked. The character has a rectangle collider with a width and height in tiles. Is there an algorithm for finding all the tiles the rectangle will overlap when moving in a straight line from A to B on the tile grid?

There is a , and numerous examples, on how to efficiently perform collision detection for a line with a grid. However, I'm drawing up blanks on how to do the same thing but with a line that has thickness. In my game, I'm considering adding projectiles that are not infinitly thin (for example, a giant plasma ball launcher), and I need to figure out which cells along a grid that it collides with. Initially I thought it'd be as simple as just using the Minkowski Sum method of adding the width/height of the projectile to each cell of the grid, and then treating the projectile as infinity thin line along a bloated-overlapping-grid, but that doesn't look like it's going to work with the existing algorithm. Are there any other papers/algorithms that describe how to accomplish this? Or is there a way to modify the existing algorithm to accomplish this? Or are there any tricks to implementing this indirectly?


For f(n) = f(n/2) + 1 where n is power of 2 (n >= 2), with f(1) = 1, Is it going to be f(n) = O(logn), f(n) = O(loglogn), or f(n) = O(sqrt(logn))  I believe its the first one but I am not sure how to verify.

Most people with a degree in CS will certainly know what . It helps us to measure how well an algorithm scales.   But I'm curious, how do you calculate or approximate the complexity of your algorithms?


In Minkowski space, the equation of motion is  $$a^c=\frac{d^2}{d\tau^2}x^c(\tau)=0.$$ How is this derived?

We know that the equation of motion of particle can be derived from the respective action. But in the book I am reading, the author is saying:     ... timelike worldline of a massive particle is parametrised by proper time, $x^a=x^a(\tau)$. The velocity (tangent) vector is $u^a \equiv \dot{x}^a(\tau)$. This is normalised as $u^au_a =-c^2$.   How can one derive e.o.m?


I'm from Germany and me and my friends want to fly to Las Vegas, America. I was there two years ago with my parents and now I want to make a roadtrip with my friends in July 2016.  The problem in this case is that I got a German and Iranian passport. Two years ago, it was not a big deal, when I was signing myself for ESTA, but now I read something about a new law, where it's not allowed for German citizens who got an Iranian passport to fly to the US with the regular ESTA Program.   My question is therefore:   Is this law already applied ?  And if no, can I sign myself up for ESTA right now? Is it regular counting for two years ? So if this new law is coming, I'm not concerned with this matter, because I sign myself up, when the law was not applied? I would then sign up today and fly in July 2016. That's what I'm thinking about. The last time I signed myself up for the ESTA Program, we got a hotel in Vegas, which I also write in the program form. In this case, we want to book the hotel when we arrive in Vegas and not from Germany (it's cheaper to book in Vegas) so we don't have an address right now. So, it's OK, when I don't have adress where we're gonna stay? Or can I write in the hotel we want to stay? I'm worried that our case will be denied, if we don't have a stay.

I've been invited by a company to a release event of a new game next month in the USA which I'd like to go there. I was born in Germany, have the German citizenship and a German passport (just ordered) which should allow me to apply for the Visa Waiver Program, but I am afraid I'll be rejected as soon as I land in America and sent back to Germany because of   My name, which does not sound much German The fact that my parents were born in Iran   Are my concerns justified? What could happen when I arrive?


In the Elsevier review system, my paper status was initially "with editor" then "under review" then "under editor evaluation" then "decision in process" and now again "with editor."  What does this mean?

What steps does a manuscript typically go through from submission to publication (or rejection) in a typical journal? How are these steps referred to, in particular by editorial systems, and how long do they each typically take?  Note that this question is about the typical situation and hence not about:   Journals with an atypical workflow, e.g. those that allow for an instantaneous reviewer–author interaction. Exceptional steps or rare occurrences such as withdrawal or .   This is a canonical question on this topic as per . Due to its nature, it is rather broad and not exemplary for a regular question on this site. Please feel free to improve this question.


I have multiple divs(containing input fiels with some unique id in each) which were created dynamically by ejs so they all contain same class name.  I want to make ajax call from only that one div's form(matching the unique id) using jquery. How can i do that?   I found lots of similar questions on google but not what i am looking for. Also before you mark this for duplicate, atleast help me with this.  This is my code:   In ejs:   <% elements.forEach(e => { %>   <input class="uniqId" value="<%=e.id%>">   <button type="button" class="btn"> <% }) %> //looping through all the data i have and storing unique value in input field   In the javascript/jquery part:  $('.btn').on('click', () => {     $('input.uniqId').val();      //and then i want to perform ajax call from that specific input field data(the one whose button i clicked) });

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.


How can I stream a 50GB large file in perl to execute some regex for each line (or chunk)? I have tried with plain vanilla   for $line (<FH>) {    # do regex }   I have also tried Tie::File and File::Stream, but perl always tries to load the whole file into memory which is simply not possible.  #!/usr/bin/perl  use IO::Handle; use Tie::File; use File::Stream; #tie @array, 'Tie::File', $ARGV[0] or die "could not open file";  STDOUT->autoflush(1);  $file=$ARGV[0]; open(INFO, "< $file") or die("Could not open  file.");  print "opening ... \n"; my $stream = File::Stream->new(<INFO>);  #$out = $ARGV[1]; #open(my $OH, '>', $out) or die "Could not open file '$out' $!"; print "starting ... \n"; while (<$stream>)  {     $line = $_;     $line =~ s/\n/\[!BR!\]/g;     $line =~ s/<page>/\n<page>/g;     $line =~ s/<\/page>/<\/page>\n/g;     print $line;      #STDOUT->flush(); }  close(INFO);

I have a filehandle FILE in Perl, and I want to iterate over all the lines in the file.  Is there a difference between the following?  while (<FILE>) {     # do something }   and   foreach (<FILE>) {     # do something }


I'm an American citizen. I was born in the US, however I came to visit Ecuador on an emergency basis using my Peruvian passport. I lost my US passport and had no time to get one before coming to Ecuador. Can I fly back to the US with my Peruvian passport only or will I be denied entry? I have my US drivers license, and SS card on me. I don't have a visa since I am a citizen and resident in the US.

I am a dual citizen. I have both a US passport and a non-US passport. I live in the US. My US passport is currently being processed for renewal. I am unsure whether I will receive my passport in time for a trip that I have scheduled. Could I use my non-US passport to leave the US and return? I have never entered the US with my non-US passport. There is no immigration leaving the US but I still need to scan my passport for ticketing. Will the airline refuse me a ticket? I know that in this situation returning with a non-US passport can be problematic as well, but will I be able to leave at all? Note that I am traveling to a country which neither of my passports are from.


I have one input file and run some command but want the output to be saved with the same name as the input file has.  I tried below command but it makes the output file blank:  cat file1 | grep "YISHA" > file1

Is there a way to modify a file without writing the contents to another file, without sed and awk?  For example:  $ cat test.txt aaa aaa bbb ccc ddd   Replacing using sed with -i option, sed -i 's/aaa/NNN/g' test.txt will produce the following:  NNN NNN bbb ccc ddd   How to do that without awk and sed?


Please tell me what is energy in reality and how can I imagine it . Please don't rearrange the question . Thanks

The simplistic undergrad explanation aside, I've never really understood what energy really is. I've been told that it's something when converted from one kind of something to another kind, or does some "work", as defined by us, but what is that something?  Moreover, if the total amount of energy in the universe is finite and we cannot create energy. Then, where did it come from? I've learned from thermodynamics where it goes, but where does it come from?  I know this sounds like something trivially simple, but there is so much going on in the physical universe and I just can't grasp what it is. Maybe it is because I lack the mathematical understanding that I can't grasp the subtle things the universe is doing. Still, I want to understand what it is doing.  How do I get to the point of understanding what it's doing?  (Note: What prompted me to ask this was . I'm afraid that it just puzzled me further and I sat there staring at the screen for a good 10 minutes.)


When setting a custom status code response with PHP using header() is:  header("Status: 404 Not Found");   Correct, or:  header($_SERVER["SERVER_PROTOCOL"] . " 404 Not Found");   Which is the http standard? Or, should you set both?

if (strstr($_SERVER['REQUEST_URI'],'index.php')) {     header('HTTP/1.0 404 Not Found'); }   Why wont this work? I get a blank page.


I am trying to set up a client socket in my android app. On a button press, I am trying to start an async task that connects to a socket and determines if the connection was successful.   public class MainActivity extends Activity {  public Socket mySocket; String str1 = "default"; private static final int SERVERPORT = 34776; private static final String SERVER_IP = "172.24.1.1";   @Override public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);  }  public void onClick(View view) {     StatusCheck myStatusCheck = new StatusCheck();     myStatusCheck.execute();          Context context = getApplicationContext();         CharSequence text = str1;         int duration = Toast.LENGTH_SHORT;         Toast toast = Toast.makeText(context, text, duration);         toast.show();  }  private class StatusCheck extends AsyncTask<Void, Void, Void> {       @Override     protected Void doInBackground(Void... params) {         //debug vibrations and text         Vibrator vib = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);         vib.vibrate(100);         str1 = "test2";         try {             InetAddress serverAddr = InetAddress.getByName(SERVER_IP);              mySocket = new Socket(serverAddr, SERVERPORT);          } catch (UnknownHostException e1) {             e1.printStackTrace();         } catch (IOException e1) {             e1.printStackTrace();         }          str1 = "test";          if (mySocket.isConnected()) {             str1 = "Connected";             vib.vibrate(500);         } else {             str1 = "Not Connected";             vib.vibrate(1000);         }          return null;     }  } }   When I hit the connect button, I display str1 in a toast message. When I first hit the button, the message is "default" as expected. The phone vibrates shortly. On subsequent presses of the button, the message changes to "test2". However, the phone does not vibrate anymore. This tells me the code is hung up somewhere in the try block. After a minute or so, the app crashes with this error:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.net.Socket.isConnected()' on a null object reference   This tells me that mySocket remains null and is not set, yet I have code right above it that should define mySocket. What I don't understand is why mySocket is not getting defined. Any ideas on how to fix this? Thank you for any help!

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


I want to add the first digit of a string 111 to the integer x = 0 so that it equals  x = 0 + 1 = 1  The following code takes the character 1 instead of the integer 1:  int x = 0; string str = "111"; x += str[1];   std::stoi did not work either:  x += std::stoi(str[1]);

I have a string of digits, e.g. "123456789", and I need to extract each one of them to use them in a calculation. I can of course access each char by index, but how do I convert it into an int?  I've looked into atoi(), but it takes a string as argument. Hence I must convert each char into a string and then call atoi on it. Is there a better way?


After I press ctrl + alt + f4 the virtual terminal appears but I can't exit anymore because it is always back to "input username" and "password". Any idea how to go back to my desktop?

I tried to install an nvidia driver and there was an error saying I must not be in an X terminal when doing so. So I did a Ctrl+Alt+F1.  The resulting terminal did not allow the nvidia driver to be installed and showed the same error message. How do I revert back to the Unity GUI?


I'm a little curious as to if there is a possibility of how I could change the color of the Windows 10 taskbar Windows button into the colors of the Windows logo, as opposed to one color accent. I am aware of the "Classic Shell.exe" approach, where I can select an image of a custom Windows start menu bottom. However, I would like to know if it is possible to do this in a more clean and natural way, such as changing a system file. I have attached a simple drawing of what I want to achieve: Original:  What I want to do:  I have very limited knowledge about programing but could find my way around using tutorials if someone could suggest an approach that could lead me onto the correct path somehow.

I want to change the icon in the start menu:    I'm willing to mess with the Registry, and I am well aware that I should make backups (and do!)  How will I accomplish this?


I sincerely hope this question is interesting for you to answer.  Assume that $V\in\mathbb{R}^{1\times k}$, $B_i\in\mathbb{R}^{k\times 1}$, $T_i\in\mathbb{R}^{k\times k}$ with $i=1\dots k$, and, finally $L\in\mathbb{R}^{1\times k}$. I've the following equation to solve for V (all other matrices are assumed to be known):  $$\begin{equation} V - VB_1VT_1 - VB_2VT_2 - \dots - VB_kVT_k = L\end{equation}$$  I would like to know if such an equation can be classified as a particular equation with known solution, for example, a Sylvester equation (I know that the proposed equation is nonlinear though), or any other type, such that the solution can be found in a closed-form expression.  Thanks!!!!

I've to solve the following nonlinear matrix equation, and I was wondering if there is any bigger class where to fit such an equation so that I can either:   Obtain a closed-form solution (ideal) Use appropriate algorithms to solve it numerically.   Assume that $V\in\mathbb{R}^{1\times k}$, $B_i\in\mathbb{R}^{k\times 1}$, $T_i\in\mathbb{R}^{k \times k}$ with $i=1,\dots,k$, and finally $L\in\mathbb{R}^{1\times k}$. The equation reads:  $$V - \sum_{i=1}^{k} VB_iVT_i = L$$  And it has to be solved for $V$ (all the other matrices are assumed to be known). Any help or suggestion will be extremely appreciated! Thanks!!!


Big tiles make the floor look bigger. Big tiles make the floor looks bigger. Which one is correct? According to my logic, the second verb of this sentence would be looks as its subject is the floor which is a third person singular number. Or it would be look for any other reason? Please let me know with explanation.

If I use the word "make" before a verb, shall I add "s" to the verb coming after it?  The mechanism makes the device operates and retries.  Or  The mechanism makes the device operate and retry.


I need to open mc.jar, but everyone says its in bin, but for me bin only has backups in it! someone help please! (P.S I am 1.8.7)

The other day I was trying to download something for Minecraft and it involved my bin folder. So I was looking for it and couldn't find it. I then thought that I might have accidentally deleted it, but didn't find it in the trash. I have no idea how to get the bin folder back with all the Minecraft binary files in them.


My mother was using a Windows machine and writing a document for a long days. Unfortunatelly, no backups of the document (Word).   Something happened during the boot process, she pressed a few times Enter and.. Windows recovered itself - it is like a new pc from shop..  Now is the question, how to recover this Word document..  so Far my plan is:  1) boot Linux from cd  2) connect usb disk (maybe I need to mount it too?)  3) lsblk for list how my internal disk is marked  4) using dd if=/dev/hda of=./part1.image (paths will be changed) to create a disk image from internal disk at external usb disk  5) then I can use another PC and try to recover files from disk image (win/Linux..)  so my question is:  is my approach correct?  how to mount external disk (or is there automount?)  what software I should use to recover files from disk image? (win or Linux, I have dualboot on my PC).  thanks a lot!

About two weeks ago I had a problem with my PC that my brother wrote a question about at .  I still haven't solved the problem, so my PC is unusable now.  Now I think that it would be simpler to re-install both Win7 & Ubuntu than repair them, but there're some data on their partitions. I want to recover this data.  These partitions are not mountable for some reason. I don't know why.  sudo fdisk -l about the problematic partitions:     Device    Boot      Start         End      Blocks   Id  System /dev/sda1            2048     147912703    73955328   83 Linux /dev/sdb2            206848   174079999    86936576    7  HPFS/NTFS/exFAT   And in GParted:      And the error of the mount command:  Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   And the exact same message for /dev/sda1  How can I recover my data from those HDDs?  EDIT     I have tried to specify the type of the drive:  $ sudo mount -t ext4 /dev/sda1 /olddisk mount: wrong fs type, bad option, bad superblock on /dev/sda1,        missing codepage or helper program, or other error        In some cases useful info is found in syslog - try        dmesg | tail  or so $ sudo mount -t ntfs /dev/sdb2 /olddisk NTFS signature is missing. Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   EDIT     sudo ntfsfix /dev/sdb2 returns:  Mounting volume... NTFS signature is missing. FAILED Attempting to correct errors... NTFS signature is missing. FAILED Failed to startup volume: Invalid argument NTFS signature is missing. Trying the alternate boot sector Unrecoverable error Volume is corrupt. You should run chkdsk.


I move in search of opportunity.   When I was young, my father worked for the government, and we moved because of his posting.   Then I moved to a different city so I could get cheap education. Later, I moved to   yet another city to get a job. I have lived outside my home state more than inside, which makes me wonder if I can call it my "home state" at all.  Is there a (single) word for people like me who move in search of opportunities?  I found in  the phrase 'bird of passage' which is a hypernym, but not an exact match:     bird of passage [noun] [literary]      someone who keeps moving from one place to another

I can't think of the word to describe it. Something similar to "wanderer" or "roamer".   It's often used to describe people that don't stay in one place... not "migratory"...


Earth's magnetic field changes over time because it is generated by a geodynamo   -Wikipedia   A time-varying magnetic field can produce electric field. So does the earth has electric field due to changing magnetic field?

Since the Earth has a magnetic field, can it, in theory, be run through a conductive metal coil to create electricity?


I am trying to configure ip address of network interfaces through terminal in ubuntu systems. So far successfully changed the IP address and other things through editing the interface file in the directory /etc/network/interfaces.  Is there any possibilities in changing the ip address of the interface through terminal using commands like configuring ip address of the router.  Thanks,Mohan

I am trying to change my IP address using terminal commands.  When I use ifconfig 10.10.10.134 netmask 255.255.255.0 I can change the IP address and can still connect to my network (I can ping other devices), but I can no longer connect to the internet. Is there something else I should be doing, or even a different command I should be using?


There's a program called MBRfix by Kåre Smith in Norway. It must be run with ADMIN privileges, and it requires multiple parameters... so, a user cannot simply right-click on it and choose "Run as administrator"! In order to use this program to help very inept users (like many old, first-time computer users with Windows 10, or 8 or 7), I need to create a batch/cmd file for them to simply click on and run; or at the most, right-click on and choose "Run as administrator". But if I do that with this batch file: @echo off echo. MBRFIX.EXE /drive 0 savembr Disk0MBR echo. echo. pause  It always comes back with: " 'MBRFIX.EXE' is not recognized as an internal or external command, operable program or batch file." (I've used both .bat and .cmd files, and in fact, it doesn't matter if you have any parameters/arguments at all, Win 10 simply will not run any program as ADMIN from inside a batch file like this!) I am working on coding my own program to open the Win UAC and ask user to run as ADMIN with built-in commands... But that will be very tedious compared to using Kåre's ready to go program. The reason neither "runas" nor "psexec" can be used is: They both require an ADMIN account with a login password... Well, my PC does not have one (on purpose) and neither do many other users who've had their PCs set up with good security (or, they were never set up as ADMIN). So, is this possible?  Or must we either school the inept user on how to open an ADMIN command prompt window (or PowerShell window) and use specific commands to navigate and parameters from a webpage or email in order to finally use mbrfix. Dan, TheStarman.

I have a batch file which is in a directory and must be run from there as well because it updates files within this directory. This works perfectly fine, except when the user runs the batch file as administrator (required on Vista). Then the starting directory is C:\Windows\System32. Is there any way to still be able to know from which directory the batch file was run? I dont want the user to enter the directory manually.


There’s  in which the user argues that regular expressions cannot be used to parse HTML … while his sanity slowly slips out of his grasp.  Unfortunately, the insane use of Unicode combining characters influence of the unholy child means that no browser can really render the text correctly. At any rate, it looks something like this (excerpt):    I tried rendering the poem in XeLaTeX (mostly to try out to what extent that would work). But to my huge disappointment, the compilation fails right from the outset. How would I go about compiling such a document in XeLaTeX? What do I have to pay special attention to? My attempts yield this error when running xelatex file:     xdvipdfmx:fatal: CID count > 65535      Output file removed.   (see the transcript file for additional information)   Error 256 (driver return code) generating output;   And no output file is produced.  Here’s minimal document to illustrate the problem:  \documentclass{scrartcl}  \usepackage{fontspec}  \def\st#1{#1} \setmainfont{Hoefler Text} \setsansfont{Gill Sans} \setmonofont{Source Code Pro}  \begin{document} You can't parse [X]HTML with regex. Because HTML can't be parsed by regex. Regex is beautiful the f\texttt{inal snuf}fing o\emph{f the lie\textbf{s of Man ALL IS LOŚ͖̩͇̗̪̏̈́T A}}\textbf{LL IS L}OST th\emph{e pon̷y he come}s he c̶̮om\st{es he co}\textbf{\st{me}s t\emph{he} ich}or permeat\emph{es al}l MY FAC\emph{E MY FACE ᵒh god n\textbf{o NO NOO̼}}\textbf{OO N}Θ stop t\emph{he an*̶̙̤͑̾̾̅ͫg͇̫͛͆̾ͫ̑͆l͖͉̗̩̳̟̍ͫͥͨ}e̠̅s\texttt{ ͎a̧͈͖r̽̾̈́͒͑e} n\textbf{ot rè̑ͧ̌aͨl̘̝̙̃ͤ͂̾̆ ZA̡͊͠͝LGΌ ISͮ̂҉̯͈͕̹̘̱ T}O͇̹̺ͅƝ̴ȳ̳ TH̘\textbf{Ë͖́̉ ͠P̯͍̭O̚N̐Y̡ H̸̡̪̯ͨ͊̽̅̾̎Ȩ̬̩̾͛ͪ̈́̀́͘ ̶̧̨̱̹̭̯ͧ̾ͬC̷̙̲̝͖ͭ̏ͥͮ͟O̮̪̝͍ͮM̲̖͊̒ͪͩͬ̚̚͜Ȇ̴̟̟͙̞ͩ͌͝}S̨̥̫͎̭ͯ̿̔̀ͅ \end{document}   I’ve chosen fonts that have many Unicode characters defined. There are probably better choices, though. Here’s .  Is there any chance with current technology to (a) compile the document and (b) make it render correctly (i.e. as intended by the Unicode standard)? Is it necessary (or even possible) to replace the Unicode diacritics with LaTeX commands to render them correctly?

Today, once again, the  came to my attention and I have decided to try to  using XeLaTeX. The result is far from perfect, worse even than Chrome's rendering.  Is there a way I can improve the result? Is XeLaTeX and LuaLaTeX incapable of handling the Ponny?  :  \documentclass[]{article} \usepackage{lmodern} \usepackage{amssymb,amsmath} \usepackage{ifxetex,ifluatex} \usepackage{fontspec} \defaultfontfeatures{Mapping=tex-text,Scale=MatchLowercase} \IfFileExists{upquote.sty}{\usepackage{upquote}}{} \IfFileExists{microtype.sty}{\usepackage{microtype}}{} \usepackage[normalem]{ulem} \setmainfont{Doulos SIL}  \title{html - RegEx match open tags except XHTML self-contained tags - Stack Overflow} \date{} \author{StackOverflow}  \begin{document} \maketitle  Rege̿̔̉x-based HTML parsers are the cancer that is killing StackOverflow \emph{it is too late it is too late we cannot be saved} the trangession of a chi͡ld ensures regex will consume all living tissue (except for HTML which it cannot, as previously prophesied) \emph{dear lord help us how can anyone survive this scourge} using regex to parse HTML has doomed humanity to an eternity of dread torture and security holes \emph{using rege}x as a tool to process HTML establishes a brea\emph{ch between this world} and the dread realm of c͒ͪo͛ͫrrupt entities (like SGML entities, but \emph{more corrupt) a mere glimp}se of the world of reg\textbf{ex parsers for HTML will ins}tantly transport a p\emph{rogrammer's consciousness i}nto a w\emph{orl}d of ceaseless screaming, he comes\sout{, the pestilent sl}ithy regex-infection wil\textbf{l devour your HT}ML parser, application and existence for all time like Visual Basic only worse \emph{he comes he com}es \emph{do not fi}ght h\textbf{e com̡e̶s, ̕h̵i}s un̨ho͞ly radiańcé de\emph{stro҉ying all enli̍̈́̂̈́ghtenment, HTML tags \textbf{lea͠ki̧n͘g fr̶ǫm ̡yo͟ur eye͢s̸ ̛l̕ike liq}uid p}ain, the song of re̸gular expre\sout{ssion parsing} will exti\emph{nguish the voices of mor\textbf{tal man from the sp}here I can see it can you see ̲͚̖͔̙î̩́t̲͎̩̱͔́̋̀ it is beautiful t}he f\texttt{inal snuf}fing o\emph{f the lie\textbf{s of Man ALL IS LOŚ͖̩͇̗̪̏̈́T A}}\textbf{LL IS L}OST th\emph{e pon̷y he come}s he c̶̮om\sout{es he co}\textbf{\sout{me}s t\emph{he} ich}or permeat\emph{es al}l MY FAC\emph{E MY FACE ᵒh god n\textbf{o NO NOO̼}}\textbf{OO N}Θ stop t\emph{he an*̶̙̤͑̾̾̅ͫg͇̫͛͆̾ͫ̑͆l͖͉̗̩̳̟̍ͫͥͨ}e̠̅s\texttt{ ͎a̧͈͖r̽̾̈́͒͑e} n\textbf{ot rè̑ͧ̌aͨl̘̝̙̃ͤ͂̾̆ ZA̡͊͠͝LGΌ ISͮ̂҉̯͈͕̹̘̱ T}O͇̹̺ͅƝ̴ȳ̳ TH̘\textbf{Ë͖́̉ ͠P̯͍̭O̚N̐Y̡ H̸̡̪̯ͨ͊̽̅̾̎Ȩ̬̩̾͛ͪ̈́̀́͘ ̶̧̨̱̹̭̯ͧ̾ͬC̷̙̲̝͖ͭ̏ͥͮ͟O̮̪̝͍ͮM̲̖͊̒ͪͩͬ̚̚͜Ȇ̴̟̟͙̞ͩ͌͝}S̨̥̫͎̭ͯ̿̔̀ͅ  \end{document}   UPDATE  Using the Doulos SIL font gets me something closer to what Firefox renders but still far from perfect.