Get:2 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libxatracker2 amd64 17.0.7-0ubuntu0.16.04.2 [1,106 kB] Err:2 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libxatracker2 amd64 17.0.7-0ubuntu0.16.04.2   Hash Sum mismatch Get:1 http://archive.ubuntu.com/ubuntu xenial-security/main amd64 firefox amd64 57.0+build4-0ubuntu0.16.04.5 [43.6 MB] Err:1 http://archive.ubuntu.com/ubuntu xenial-security/main amd64 firefox amd64 57.0+build4-0ubuntu0.16.04.5   Hash Sum mismatch Fetched 88.4 MB in 3min 20s (441 kB/s)                                          E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/f/firefox/firefox_57.0+build4-0ubuntu0.16.04.5_amd64.deb  Hash Sum mismatch  E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/m/mesa/libxatracker2_17.0.7-0ubuntu0.16.04.2_amd64.deb  Hash Sum   mismatch  E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

When I check for updates, I get a "Failed To Download Repository Information" error.   This is what comes up under details:   W: Failed to fetch gzip:/var/lib/apt/lists/partial/us.archive.ubuntu.com_ubuntu_dists_natty_main_source_Sources  Hash Sum mismatch,  E: Some index files failed to download. They have been ignored, or old ones used instead.


I am trying to include a page of another pdf (in another folder) into a TeX file as it compiles. The other document has spaces in the title as well as in the path.  \documentclass[12pt]{article} \usepackage{grffile} \usepackage{pdfpages}  \begin{document} \includepdf[pages=6]{../AP Exams/2005 Form A/2005AFRQv2} \end{document}    I end up with an off-center image of the page preceded by the path in the command on the left side. Does anyone know how to fix this? I'm using XeLaTeX for reasons not shown in this MWE.

I am trying to use \includepdf with about 20 different PDFs. The first 19 have worked fine, but the last one which can be found below     will not load properly. However, there are no errors - the PDF produced just has a blank page with a couple of black lines in the middle. I converted the PDF to JPG and used \includegraphics and it loaded properly but then I could not add it to my table of contents in the way I wanted.   Any thoughts on why it won't load as a .pdf but will as .jpg?  Here's a minimal document that shows the problem:  \documentclass{article} \usepackage{pdfpages} \begin{document} \includepdf{analysiscompsSprJan2011.pdf} \end{document}


How do I solve this definite integral?   $$I =\int_{-2}^2  \frac{x^2}{1+5^x}dx $$   Is there any way to solve this integral using high school calculus. P.S This was asked in the recently conducted CBSE Exams in India.

$$\int^2_{-2}\frac{x^2}{1+5^x}$$  How do I start to integrate this?  I know the basics and tried substituting $5^x$ by $u$ where by changing the base of logarithm I get $\frac{\ln(u)}{\ln 5}=x$, but I got stuck.  Any hints would suffice preferably in the original question and not after my substitution.  (And also using the basic definite integrals property.)  Now I know only basic integration, that is restricted to high school, so would prefer answer in terms of that level.


I saw that some quite similar questions have already been asked on the forum, but, still, I can't find a way to solve my problem.  I've just installed the mactex package 2015 from  and then installed TeXworks. Now, when I try to compile any file I get the following error message:  It's in italian and it means that program "pdflatex" has not been found and that I need a TeX distribution like MacTex.   The point is that I've already installed the Mac distribution!  Any help?

Now here is the thing. I upgraded my Mac to the OS X EI Capitan a few days ago. And now MacTeX is not working. When I try to typeset it, the console shows the following error:   xelatex: command not found.  How can I fix it?


Do you know how to recover media files from iPhone 6? I lost my photos and music by some accident.

I used an iPhone 3G from May of 2009 until around the spring of 2013, at which time I upgraded to the iPhone 5. I've always been a prolific iPhotographer :) and recently pulled around 12,000 photos off my iPhone 5 for backup and to free up disk space. I've kept the old iPhone 3G, though, and suspect it has thousands of pictures on it that need to be removed from the phone and backed up on my cloud, my laptop, and an external hard drive. However, Apple no longer makes available the OSX that supports and grants access to an iPhone 3G through iTunes. I can't hook it up to my laptop (Dell XPS 15Z, if it helps to know what I'm running, with Windows 7) and access the pictures to manually move them off the phone.  How do I recover pictures from an iPhone 3G? Is there anything that can be done?  Is there anything that can be done? As it is, I can't get my computer to even see the 3G, much less charge the phone through the computer or allow me to access the phone's drives and my pics. I'm currently charging the 3G via wall plug/USB, which I think will allow me to look at my photos on the phone itself once the phone is juiced up ... but I really just want to recover and transfer my images off the iPhone 3G for safekeeping.  I did search this site prior to posting and could not find my exact question. Please don't hesitate to VTC if I've accidentally submitted a duplicate.


Hi I have a python code written as followed. Can someone please explain what these colons do?  edges = (data[0,0:-1]+data[0,1])/2.0     counts = data[1,1:]

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


I am writing my minor thesis which includes a number of tikz figures, which are all listed in a table of figures.  the table of figures gives the figure number, and then the title of the figure, as given by the caption.  the way i have put them into my document is in the following manner:  % ---------------- \begin{figure}[h!] \centering \includegraphics{./tikz/network.tikz} \caption{Feed-forward neural network - The red line indicates the path a signal travels from input node $x_2$ to output node $y_4$.} \label{fig:network} \end{figure} %-----------------   My problem is that the whole caption is being printed in the list of figures, and i would like it only to have "Feed-forward neural network" in the list of figures.  I would be greatly appreciative if someone could explain to me how i can separate the figure title from extended description.  thanks

I am using the 'article' class, 'figure' environment.  My captions are divided in two parts:   the information about the figure the credits of the figure (for which I use \textfff{})   In my list of figures, I would like to omit the second part. Would you have a solution, please?


Prove that if $n\geq1$ then $$\binom{2n}{n}=\sum_{k=0}^{n}(\binom{n}{k})^2$$    This is what I have so far:   By the Binomial Theorem: $$\binom{2n}{n}=\frac{(2n)!}{(2n-2)!n!}=\frac{2n!~}{n^2(n-1)^2(n-2)^2...1}$$  By the definition of summation: $$\sum_{k=0}^{n}(\binom{n}{k})^2=(\binom{n}{0})^2+(\binom{n}{1})^2+(\binom{n}{2})^2+(\binom{n}{3})^2+...+(\binom{n}{n})^2$$  By the Binomial Theorem => $$\sum_{k=0}^{n}(\binom{n}{k})^2=1^2+(\frac{n!}{(n-1)!})^2+(\frac{n!}{(n-2)!2!})^2+(\frac{n!}{(n-3)!3!})^2+...+1^2$$  $$=1+\frac{n!n!}{((n-1)!)^2}+\frac{n!n!}{((n-2)!)^2(2!)^2}+\frac{n!n!}{((n-3)!)^2(3!)^2}+...+1$$  This is where I get stuck. I'm not sure how to continue from here. I know that what I am getting is starting to look a lot like what I want it to look like but I don't know how to finish, nor am I sure that I've done it correctly to this point. Help?

I was hoping to find a more "mathematical" proof, instead of proving logically $\displaystyle \sum_{k = 0}^n {n \choose k}^2= {2n \choose n}$.  I already know the logical Proof:  $${n \choose k}^2 = {n \choose k}{ n \choose n-k}$$  Hence summation can be expressed as:  $$\binom{n}{0}\binom{n}{n} + \binom{n}{1}\binom{n}{n-1} + \cdots + \binom{n}{n}\binom{n}{0}$$  One can think of it as choosing $n$ people from a group of $2n$  (imagine dividing a group of $2n$ into $2$ groups of $n$ people each. I can get $k$ people from group $1$ and another $n-k$ people from group $2$. We do this from $k = 0$ to $n$.


Want to get the IP address using Shell script. Without knowing the eth0 or eth1 or eth2 How to get the particular IP address.  I am not interest to get localhost address, want to get private IP address.

I need to find my external IP address from a shell script. At the moment I use this function:   myip () {      lwp-request -o text checkip.dyndns.org | awk '{ print $NF }' }   But it depends on perl-libwww, perl-html-format, perl-html-tree installed. What other ways can I get my external IP?


Is there a way for me to obtain my 5th gen pokemon without.. A) Using the Pokebank. B) Trading each pokemon individually with a willing friend?

I know that you can trade Pokemon between games of the same generation (Gold/Silver, Ruby/Sapphire) and even trade between 1st gen and 2nd gen. However, I haven't been able to find a way to trade Pokemon so that I can play with my 1st generation Pokemon in HeartGold, for instance. If it is possible, how many steps would it take and what equipment would I need?


Tried Remmina (VNC) but only managed to do it on the local network.

How do I remotely control another desktop (both are Ubuntu 12.04) from my client machine?  Is it possible to use Remmina Remote Desktop Client?


I was sleeping in the dark when I reached over for my blanket. It slipped out between my fingers and made a light spark. I repeated in different parts of the blanket at least ten times. I can't understand why this is happening. I rubbed another blanket and my fingertips still sparked. Why does this happen?

Sometimes when I'm in bed at night, I rub my feet against the sheets and light is created. What exactly is going on?     I'm familiar with static electricity, and the triboelectric effect (creating a charge by rubbing 2 insulators together), and electrostatic discharge (releasing charge by touching a grounded conductor).     I believe that all of that is what is at work here, but I'm slightly confused since in other cases, the triboelectric effect and electrostatic discharge seem to occur as two separate steps, with different substances involved, and here, the two effects seem to be occurring simultaneously, with the same substances.     Can someone help me with a step-by-step explanation of the dynamics of what is going on?


I cannot comprehend why there are so many games available for windows and so few for linux in comparison. Why is the main reason, is it a technical or business reason ?  Are Windows libraries (directx) better or is it because of the driver support ? Linux have some great libraries like Allegro , SDL and LibGlut. And Android is Linux after all.  Given all that Why are more games in windows than linux ?.

What is wrong with the Linux/*nix family for games? What makes the development of games for this platform too slow compared to Windows or even OS X?


$(X,d)$ metric space and $A\subset X$ and $A$ is connected. $$ \text{Card}(A) > 2 \implies \text{Card}(A) \geq \text{Card}(\mathbb{R}).$$  How do I prove it ?Waiting for your help?

As the topic, how to prove that every connected metric space with at least two points uncountable? Of course i know the definition that a countable set mean there is a bijection between the set and the positive integer. Connected is opposite of disconnected where the set can partition into two disjoint open sets.


Does charge bend spacetime like mass?   I'm not asking if electromagnetic forces can be described geometrically, but if EM fields could correspond to particular curvatures of spacetime, like gravity which arises from the spacetime bending due to the stress-energy tensor.    Is it true in the three spacial dimensions we observe? Is it plausible in other dimensions (for example the fourth dimensions of the Kaluza-Klein theory)?

It is written everywhere that gravity is curvature of spacetime caused by the mass of the objects or something to the same effect. This raises a question with me: why isn't spacetime curved due to other forces or aspects of bodies?  Why isn't it that there are curvatures related to the charge of a body or the spin of particles or any other characteristics?


I have Ubuntu 17.04 on my Asus laptop.  After login I cannot write anything to /dev/sda6  It tells me that the disk is in read-only mode:    How can I fix it?

Whenever I boot Ubuntu, I get a message that it cannot mount my windows partition, and I can choose to either wait, skip or manually mount.  When I try to enter my Windows partition through Nautilus I get a message saying that this partition is hibernated and that I need to enter the file system and properly close it, something I have done with no problem so I don't know why this happens.    Here's my partition table, if any more data is needed please let me know.     Device Boot      Start         End      Blocks   Id  System /dev/sda1            2048    20000767     9999360   83  Linux /dev/sda2        20002814   478001151   228999169    5  Extended /dev/sda3   *   478001152   622532607    72265728    7  HPFS/NTFS/exFAT /dev/sda4       622532608   625141759     1304576   82  Linux swap / Solaris /dev/sda5        20002816   478001151   228999168   83  Linux


Let $f$ be a continuous function on $\mathbb R$ satisfying the relation $$f(f(f(x))) = x\ \text{for all}\ x \in \mathbb R$$ Prove or disprove that $f$ is the identity function.  I tried taking the derivative. From the derivative, I'm not sure about it, but I concluded it had to be of degree 1 if it is a polynomial since if it'd have been of degree 2 or higher.. there needed to be terms of $x$ in the derivative.. which are not there.

Does $f(f(f(x)))=x \implies  f(x)=x$? Is it necessary for it to follow? How do we prove this? Do we have to substitute some special $x$? Or is it some other consideration of its properties?  Edit: does it follow in the special case when f is surjective? Or would we wind up with the same thing?


/*Edited: For Blender 2.7 Users I found a detailed  with pictures. */  I want to build an VR-Scene in Unity with a little Island and and ocean around.   For the ocean I am quite happy with the ocean modifier and made already an looping animation with the water.    But I simply cannot find a solution to export the mesh + animations to Unity. I keyframed the time and scale and found the problem, that these can't update when I apply the modifier. To my understanding blender needs to apply the modifier when exporting, so I can even get the shape of Ocean.  [  I tried and failed with  explanation.  Could somebody please give me an more beginner friendly explanation?  Here is my blendfile:

It is there any way to export the foam data generated from ocean modifier to use it in other render engine, like LuxRender? The manual says that the foam data is stored as vertex color data, but there isn't a way to access the vertexColor data. I know that can be accessed from Cycles from attribute's node. LuxRender supports vertex color and I tried to bake the texture to vertexColor and an image but only get a plain black texture.


All I want to do is load information I saved to a plain text file about the position of a  and set the frame to the state it was saved as. For some reason I'm unable to compare capture groups with strings; that is, matcher.group("state") compared to the string it should be ("min", "max", or "normal") is not returning true, and the same goes with matcher.group("vis").  String fileArrayStr = "WINDOW_LAYOUT:0,0|779x768|max|show"   My code is:  byte[] fileArray = null; String fileArrayStr = null; try {     fileArray = Files.readAllBytes(PathToConfig); } catch (IOException e) {     e.printStackTrace(); } try {     fileArrayStr = new String(fileArray, "UTF-8"); } catch (UnsupportedEncodingException e) {     e.printStackTrace(); }  // checking the value of fileArrayStr here by outputting it // confirms the data is read correctly from the file  pattern = Pattern.compile(     "WINDOW_LAYOUT:\\s*" +     "(?<x>[0-9\\-]+),(?<y>[0-9\\-]+)\\|" +     "(?<length>\\d+)x(?<height>\\d+)\\|" +     "(?<state>[minaxorl]+)\\|" +     "(?<vis>[showide]+)\\s*"); matcher = pattern.matcher(fileArrayStr); if (matcher.find()) {     frame.setLocation(Integer.parseInt(matcher.group("x")),                     Integer.parseInt(matcher.group("y")));     frame.setSize(Integer.parseInt(matcher.group("length")),                     Integer.parseInt(matcher.group("height")));     DialogMsg("state: " + matcher.group("state") + "\n" + "vis: "                     + matcher.group("vis"));      // the above DialogMsg call (my own function to show a popup dialog)     // shows the     // data is being read correctly, as the values are "max" and "show"     // for state     // and vis, respectively. Same with the DialogMsg calls below.      if (matcher.group("state") == "min") {         try {             frame.setIcon(true);         } catch (PropertyVetoException e) {             e.printStackTrace();         }     } else if (matcher.group("state") == "max") {         try {             frame.setMaximum(true);         } catch (PropertyVetoException e) {             e.printStackTrace();         }     } else {         DialogMsg("matcher.group(\"state\") = \""                         + matcher.group("state") + "\"");     }     if (matcher.group("vis") == "show") {         frame.setVisible(true);     } else if (matcher.group("vis") == "hide") {         frame.setVisible(false);     } else {         DialogMsg("matcher.group(\"vis\") = \"" + matcher.group("vis")                         + "\"");     } }   The code is always falling back to the else statements. What am I doing wrong?  is supposed to return a string, is it not?

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 have 8 gb of ram and use my machine for web browsing streaming and some light gaming. Do I need a swap partition?

I have read , but it was asked in the context of servers not desktops or notebooks.  If a good amount of RAM is installed on a notebook, say 8 GB, do we still need a swap space?


I am having trouble understanding this question.  I know the total number of function is $4^6 = 4096$. There are no injective functions as the domain > co domain.  I know there is a part that I'm missing that has to do with the amount of functions that are neither surjective nor injective.  My train of thought was along the lines of (total - injective (=0) - not injective not surjective) = total number of surjective.

Let $m,n$ be two integers such that, $m\ge n$. Compute the number of surjections from $\{1,...,m\}$ to $\{1,...,n\}$   There are $n^m$ functions (total).  we subtract from $n^m$ the number of non-surjective functions.  There are $\binom{n}{1}(n-1)^m$ functions missing one element.  There are $\binom{n}{2}(n-2)^m$ functions missing two elements, but how many times did we count this in the previous count ?  Then we have to add this again by inclusion-exclusion but why is the difference always 1?


A dir I cd into a lot has a really long path. I'd like to reduce keystrokes.  I have tried this...  sudo ln -s /mnt/c/Users/me/ho/hum/bin /mybin   It works, but something about it seems wrong.  Is there a better way?  I currently use bash, but a solution that would still work if I switched shells would be nice.  System info  Running Unbutu on Windows Subsystem for Linux.  $ uname -a Linux Hostname 4.4.0-17763-Microsoft #253-Microsoft  \     Mon Dec 31 17:49:00 PST 2018  \     x86_64 x86_64 x86_64 GNU/Linux

I would like to frequently switch between directories that are in totally unrelated paths, for example /Project/Warnest/docs/ and ~/Dropbox/Projects/ds/test/.  But I don't want to type cd /[full-path]/ all the time. Are there any shortcut commands to switch to previously worked directories?  One solution I could think of is to add environment variables to my bash .profile for the frequently used directories and cd to them using those variables.  But is there any other solution to this?


I am writing my thesis in draft mode.   \documentclass[dissertation,draft]{univthesis}   The univthesis is a dissertation template like a book. However, when I include figures, I only see the figure name and box enclosing it. When draft mode is removed, I get what I want. So, I was wondering if there is a way to display images even in draft mode. I have both .eps and .pdf files in the current directory.

For collaboration purposes I am using the draft mode in my LaTeX manuscript to show todo-notes, remarks and so on. By switching to final mode all of these additions become unvisible.  However, I'd love to switch on the final mode of the graphics/x package to see the actual pictures but \documentclass being still in draft mode. I get an error about clashing options when I add  \usepackage[final]{graphicx}   My first guess was that the \documentclass already sets the option for the graphics/x package. Following doesn't help either  \PassOptionsToPackage{final}{graphicx} \documentclass[twoside,onecolumn,draft]{rsauthor}


I tried using the cases to code this, but I only can put them in two separate lines, not along the same line.

I want to write a conditional expression such as the following.    What is the best way to express such conditional expressions in Latex?


I want to get the image associated to a file based on the extension.  for example: \100xadmin\100xredirectedfolders$\elianf\Desktop\WORK\Query Coalesce.txt   I just want to get image related with .txt extension.

I have a form that displays file information in a TabControl, and I'd like the pages to have the file's icon in their tab.  How do I get the icon associated with a file type?  I'd prefer solutions that don't involve looking things up in the registry, but if that's the only way then so be it.


I want to show Frame Number/Total Frame Number without navigation bar, just like the following picture:    The below MWE works as expect:  \documentclass{beamer} %\usetheme{Copenhagen}  \beamertemplatenavigationsymbolsempty \setbeamertemplate{footline}[frame number]{}  \begin{document}  \frame { \frametitle{Frame A} Frame A }  \frame { \frametitle{Frame B} Frame B }  \frame { \frametitle{Frame C} Frame C }  \end{document}   However, if I uncomment the second line %\usetheme{Copenhagen}, the Frame Number/Total Frame Number disappears as follows:    My compiler is TexLive 2018 with xelatex.  Is there any way to show Frame Number/Total Frame Number with Copenhagen theme?

The following MWE does not print frame numbers with MacTeX 2017 (beamer v3.50, LuaTeX 1.0.4):  \documentclass{beamer} \usetheme{PaloAlto} %\beamertemplatenavigationsymbolsempty \setbeamertemplate{footline}[frame number] %\setbeamertemplate{page number in head/foot}[framenumber]  \begin{document} \begin{frame}   \frametitle{Test}   Bar \end{frame} \end{document}     But it works with TeXLive 2016 (beamer v3.41, LuaTeX 0.95.0):    Using setbeamertemplate{page number in head/foot}[framenumber] instead of \setbeamertemplate{footline}[frame number] does not help. How can I fix it?


Give a generalized form [in the form of "n" i.e number of vertices of a polygon] of the number of combinations possible for 3 colored balls [infinite balls [it is not compulsory to use all the colors]] to be placed at vertices of a polygon with n vertices. The condition to be met is that no balls of same colored to be placed adjacent to each other. We consider two colorings the same if the can be obtained from one another by rotating or reflecting the n-gon.  Conditions:   No two same colors can be placed adjacent We have only 3 types of balls and which can be used in any number as far as 1st condition is followed. Rotation or reflection pf a coloring does not count as a new coloring.   Eg: Take a case of Triangle. Possible combinations of placing balls is 1 i.e. 1 ball of each color.  Square: we can take either 2 balls each of 2 different colors or 2 balls of one color, 1 ball each of other two colors. Which gave total combinations of 6.

Given an $n$-sided polygon, how many ways can you color the vertices using $k$ colors so that no two adjacent vertices have the same color?  (Inspired by 2011 AMC 12 A #16 – I'm able to do this for small cases but not in general.)


If the roots of the equation $x^3-x+1=0$ are $a$, $b$ and $c$, then find the value of $a^5+b^5+c^5$. My attempt: I found out $a^2+b^2+c^2$ and a$^3+b^3+c^3$ but it is turning out to be extremely lengthy to find the sum of the roots raised to the $5^{th}$ power.

Can someone please help us solve this equation. It was on our college entry exam, but no one managed to solve it. The problem is:     Let $p,q,r$ be the roots of $x^3 -x+1=0$.  Then $p^5+q^5+r^5 = ?$   Correct answer was $-5$, but no one managed to solve this problem. We tried different methods, but none came up with a solution. Any help is appreciated.


I am beginning to study general relativity and one of the preconceptions that I have is that massive objects will warp space in a similar way to that described by the photo below  However my understanding is that massive objects in fact warp spacetime and that in a time and spatial coordinate system straight lines might not be straight due to the presence of massive objects.  Does this imply the warping of space as above? And if not, how can you explain the bending of light around massive objects?

I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general relativity there is this one illustration, which is being used over and over (image from Wikipedia):    I always thought that general relativity gives another way how you can describe gravity. However for this illustration to work, there needs to be another force, pulling the object down (referring to a direction in the attached image). If I put two non-moving objects in the image, what force will pull them together?  So where is my understanding incorrect? Or is general relativity not about explaining gravity and just describes how heavy objects bends spacetime (in that case the analogy is being used not correctly in my opinion)?    UPDATE Thank you for the answers and comments. Namely the XKCD comics is a spot on. I understand that the analogy with bent sheet of fabric pretty bad, but it seems that it can be fixed if you don't bent the fabric, but just distort the drawn grid.   Would you be so kind and answer the second part of the question as well - whether general relativity is explaining gravitational force. To me it seems that it is not (bending of spacetime simply can not affect two non-moving objects). However most of the time it is being presented that it does.


Now since Photons have energy too, is it possible for these particles to gravitationally attract each other.

In general relativity, light is subject to gravitational pull.  Does light generate gravitational pull, and do two beams of light attract each other?


Show that the set $ [-1, \infty )$ has cardinality of the continuum. Draw the bijection.    Answer: If I consider the map $ f: [-1, \infty ) \rightarrow (-\infty, \infty) $ by $ f(x)=\log(1+x) $.   This is one-one  and onto.   Hence the proof.  But I have doubts using $ f(x)= \log(1+x) $ because it is not defined at $ x=-1 $.  Any help is there ?

How to define a bijection between $(0,1)$ and $(0,1]$?   Or any other open and closed intervals?   If the intervals are both open like $(-1,2)\text{ and }(-5,4)$ I do a cheap trick (don't know if that's how you're supposed to do it): I make a function $f : (-1, 2)\rightarrow (-5, 4)$ of the form $f(x)=mx+b$ by \begin{align*} -5 = f(-1) &= m(-1)+b \\ 4 = f(2) &= m(2) + b \end{align*} Solving for $m$ and $b$ I find $m=3\text{ and }b=-2$ so then $f(x)=3x-2.$  Then I show that $f$ is a bijection by showing that it is injective and surjective.


I have to create two algorithms (but I think it is more of a combinatorics question).  Let there be list of permutations on elements $\{1,2,...,k\}, k \in N$ and this list is alphabetically ordered (meaning that e.q. permutations with $\pi(1) = 10$ is in this list before $\pi(1) = 2$).  1) Find position of specified permutation in that list -   e.g. input is (1, 2, 4, 3, 5) and find position, it would give 3  2) Find what permutation lies in that list on specified position -  e.g. input is 3 and I should find what permutation is on third line, that can be something like (1, 2, 4, 3, 5)  I tried to approach this as counting permutations that can be before specified one, but it seems quite complicated since $k$ can be huge number... at least for me as a combinatorics newbie.  Is there maybe some approximation that would give me some decent starting point from which I'd be able to start checking permutations manually and not having exponential time complexity?  Thanks a lot!

I have an ordered set of symbols S = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }. I want to find the 1,000,000-th permutation in lexicographic order of S. It is a programming puzzle, but I wanted to figure out a way without brute-forcing the task.  So my thinking was like this:  For 10 variable symbol positions, we have 10! permutations, obviously. Now we want to find the first symbol.  If we fix the first symbol, then the remaining 9 symbols can have 9! combinations.  That means that 0 or 1 cannot be the first symbol, because the highest possible position is 2*9! = 725,760, which is lower than 1,000,000.  The lowest position for a leading 3 is 3*9! + 1 = 1,088,641, so it can't be 3 or higher, either.  Therefore, the first number must be 2. 2*9! is the largest multiple of 9! no greater than 1,000,000, so I need the 2nd symbol (zero-based) from the current set.  So now the question becomes, of the remaining S := S \{2}, which permutation of these symbols is at lexicographic position (1,000,000 - 2*9!) = 274,240?  6*8! = 241,920 is the largest multiple of 8! which is smaller than 274,240, so I need the 6th-smallest symbol of the remaining set, which is 7. So the prefix should be 27 by now.  That way, I keep going and finally arrive at: 1,000,000 = 2*9! + 6*8! + 6*7! + 2*6! + 5*5! + 1*4! + 2*3! + 2*2! + 0*1! + 0*0!  which results in "2783905614" as my solution.  However, according to the , (free reg. req.) that is incorrect.  Where did I go wrong in thinking or applying?


I have a log-in form that I want to validate and redirect (if the username and password are correct) with jQuery, and the redirect isn't working.   This is my code:   $(document).ready(function() {     $('#lc-login').click(function() {         var username = $('#username').val();         var pass = $('#pass').val();                  if (testUser(username) === true && testPass(pass) === true) {                         window.location.replace("http://www.domain.com/home.html");         } else {             alert('warning message');         }     }); });   I've try replacing the window.location.replace with window.location.href and still nothing. I should say that the testUser and testPass are working fine, because if I add a simple alert('the validation is ok!'), the message is appearing on my screen.

How can I redirect the user from one page to another using jQuery or pure JavaScript?


I've tried doing a WP_Query based on a custom field, which name is 'date' and value is something like '14/01/2015'. I want the query to give results when 'date' is between today and tomorrow.  All I've tried so far is this:  $y=date('d/m/Y',strtotime('yesterday')); $t=date('d/m/Y',strtotime('tomorrow')); $o=date('d/m/Y',strtotime('today'));  echo "yesterday: ".$y; echo "today: ".$o; echo "tomorrow: ".$t; $d=new WP_Query(     array(         'category__in' => array(4),         'post_type' => 'post',         'posts_per_page' => '-1',         'orderby' => 'meta_value',         'order' => 'DESC',         'meta_query' => array(             'key' => 'data',             'value'     => array($y,$t),             'compare'   => 'BETWEEN',             'type'      => 'DATE',         )     ) );   But is giving me posts which 'date' is also 25/01/2015. What am I doing wrong? Thanks in advice

I am building a WP site with an events feature. The events page was made with custom post types.  I want to make it possible for people to search/ filter events by dates. For example, they can search for all events happening between 2nd December, 2011 and 1st March, 2012 and get results from events that have their dates between the months of December and March (ie. december, january, february and march).  I want to know the best way to go about this. Any ideas?  You can see an example of what I want to achieve by looking at the "Search events by date" feature on this page   If that won't be possible, is there any way I can get them to search for events happening between certain months, say December and February(excluding the days)?  Thanks in advance.


I'm trying to get DOF in Compositing from an OpenEXR image with Combined/Alpha/Mist passes. This is the combined pass:    I can get DOF by a defocus node using the Mist pass (after a ColorRamp to define better), but I can't set which part of the image is focused and unfocused. (I want the character with the knife to be focused, and not the other character).    If I invert the Mist image I can achieve this but the borders aren't unfocused:    Is there any better way to achieve this? FYI I have an alpha pass  Thank you!

Is is possible to increase the depth of field in cycles while keeping the same blur size? I know this is not physically correct, but in some renders this would be useful. Here is a demonstration of what I am looking for: Normal Focus:  What I'm trying to achieve (New part shaded green):  Is this possible (Maybe with the compositor)? If so, how? Any help is appreciated. An example for what this would be used for would be the following: I have a somewhat lengthy main object that I want in focus. The other background objects are moderately close to the main object, but I want them to be blurred. If you increase the DOF blur to ensure the background objects aren't in focus, your main object is only partially in focus. The Depth of focus is too shallow to fit your main object. Now if you change to a wide DOF, the background objects would still be relatively clear which is not what you want. The solution is what I am describing; You would set a very shallow DOF, initially, so that the background is well out of focus, and then you would increase just the focus area to cover the main object but keep the blur amount the same.


How can I install Google Chrome to a custom location, instead of its default usr/bin?  And where does Chrome keep user settings?

When I install a software using apt-get it installs to default locations i.e to /usr/bin, /usr/lib, /usr/share and etc. For example when I install "Meld Diff Viewer" using  sudo apt-get install meld   and use whereis command to find its location, I get the following output  adnan@adnan-laptop:~$ whereis meld meld: /usr/bin/meld /usr/lib/meld /usr/share/meld /usr/share/man/man1/meld.1.gz   Is there any way to change the install location. Lets say if I want to install it in /usr/local/ can I do it using apt-get or aptitude? I know I can compile it from source and specify prefix option to configure script or make install but it would be better (and really easier) if I could do it using apt-get as I would be able to use uninstall, upgrade and other stuff that apt-get offers


I just tried to install Crossover (Codeweavers) via the Ubuntu Software Center in Ubuntu 13.10 32-bit, but it didn't finish the installation. It just got stuck at about 90% (progress bar). After waiting approximately one hour, nothing happened. The installation was stuck, so I decided to restart the computer.   The issue now is: Every time I try to reinstall Crossover via Software-Center, Ubuntu gives me a message box with the following error message:   Package dependencies can not be resolved  This error could be caused by required additional software packages which are missing or not installable. Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time. The following packages have unmet dependencies crossover-trial: Depends: crossover-trial-bin (= 12.5.0-0ubuntu1 but 12.5.0-0ubuntu1 is not going to be installed)   Any ideas about how to fix it?

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


I have found this on internet as a very interesting mathematical curiosity...     If we have $x\in \mathbb{N}$, they say that if $x=\sum^{K}_{n=0}{(2n+1)}$, then $\sqrt{x}\in \mathbb{N}$ and $\sqrt{x}=K+1$.   Is that always true? Why?  This is my first question here! Thanks in advance and sorry for any mistakes.

I stumbled across this relationship while I was messing around. What's the proof, and how do I understand it intuitively? It doesn't really make sense to me that the sum of odd numbers up to $2x + 1$ should equal $x^2$.


Are there any examples of such an argument? What would its premises be like? How could such an argument be possible?  Where an argument is logically valid "if and only if it is not possible for all the premises to e true and the conclusion false."  And logically false is defined as "if and only if it is not possible for the sentence to be true." (e.g. 'June will pass Chemistry 101 and she will not pass Chemistry 101').

My text book gives the definition of validity as "An argument is valid IFF if the premises are true, then the conclusion must be true". Using a conditional elimination on the RHS of the IFF yields "An argument is valid IFF the premises are false or the conclusion is true".   Yet, this seems strange to me. Am I doing something incorrect with my manipulation or is this definition actually true? Surely the criteria for a valid argument goes beyond a false set of premises or a true conclusion.


I am using a plain JavaScript object. I have to create an exact copy of the object to make changes:  var gRoll = {a:"pankaj",b: { a:"A",b:"c" }}   var copy = gRoll; copy.a = "Karma";   This is making change in the parent object. Please give me solution to create copy of the object without referring to the old one. Same like prototype design pattern in OOPS.

What is the most efficient way to clone a JavaScript object? I've seen obj = eval(uneval(o)); being used, but . I've done things like obj = JSON.parse(JSON.stringify(o)); but question the efficiency.  I've also seen recursive copying functions with various flaws.  I'm surprised no canonical solution exists.


I found this question some time ago in an Elementary Olympiad book:  If $a, b, c, d$ are positive integers such that $abcd =1$, then prove that $(1+a)(1+b)(1+c)(1+d) \geq 16$.  Evidently this was a direct consequence of Hölder's inequality, so I merely gave the following proof. $$(1^4+(a^{\frac{1}{4}})^4)(1^4+(b^{\frac{1}{4}})^4)(1^4+(c^{\frac{1}{4}})^4)(1^4+(d^{\frac{1}{4}})^4) \geq (1+(abcd)^{\frac{1}{4}})^4 $$ $$(1+a)(1+b)(1+c)(1+d) \geq (1+1)^4$$ $$(1+a)(1+b)(1+c)(1+d) \geq 16$$ QED.  However, I was requested by my instructor to try the problem again using only the AM-GM inequality or the Cauchy-Schwarz inequality, because it is supposedly solvable using only those two. At this point I expanded the expression believing that all the terms so formed would be of the degree $4$, and would, when taken together in groups, yield a power of $abcd$ on the GM side, which could then be added. Doing so, however, I only get the weaker result that $(1+a)(1+b)(1+c)(1+d) \geq 14$. I would appreciate a hint for this tantalizing problem.

Suppose $a_1, a_2,\dots , a_n$ are $n$ positive real numbers with $a_1a_2 \dots a_n = 1$.   Then what is the minimum value of $(1 + a_1)(1 + a_2). . .(1 + a_n)$ ?    I think $(1 + a_1)(1 + a_2). . .(1 + a_n)$ takes its minimum value when $a_1=a_2=\dots=a_n=1$ and thus the minimum value is $2^n$.  I don't know how to prove it. Please help.


I have added two gifs in my code and I am trying to add text on top of it, but it ends up being on top or the bottom of the gif. How can I add something on top of a gif?  I've tried adding text and positioning it on top of the gif using relative position and absolute but that does'nt work.   HTML:  <! DOCTYPE html>     <meta charset="utf-8">  <link href="taniaWebsite11.css" type="text/css" rel="stylesheet"> <title> </title>                 CSS:  img{ height:1000px; width:1000px;  }  body.mainpage12{ background-color:black; }

I want to overlay one image with another using CSS. An example of this is the first image (the background if you like) will be a thumbnail link of a product, with the link opening a lightbox / popup showing a larger version of the image.   On top of this linked image I would like an image of a magnifying glass, to show people that the image can be clicked to enlarge it (apparently this isn't obvious without the magnifying glass).


While trying to benchmark as suggested when I asked  question, I found that no matter what, whichever piece of code I tested second was dramatically longer by a factor of 1000 ns. I even swapped the pieces of code being tested to see if one really just was longer than the other, and the longer time swapped meaning it is placement in code that affects how long it runs. Here is my benchmark code:  public class JavaAsmTest {     public static void main(String [] args)     {         int numOfTrials = 10;          long [] codeATimes = new long [numOfTrials];         long [] codeBTimes = new long [numOfTrials];         for(int trial = 0; trial < numOfTrials; trial++)         {             {                 long startTime;                 long endTime;                 long deltaTime;                 startTime = System.nanoTime();                 for(int x = 0; x < 0x10000; x++)                 {                     for(int y = 0; y < 0x10000; y++)                     {                         codeB(x, y); //the code being tested                     }//end y loop                 }//end x loop                 endTime = System.nanoTime();                 deltaTime = endTime - startTime;                 codeBTimes[trial] = deltaTime;             }//end codeB Trial             {                 long startTime;                 long endTime;                 long deltaTime;                 startTime = System.nanoTime();                 for(int x = 0; x < 0x10000; x++)                 {                     for(int y = 0; y < 0x10000; y++)                     {                         codeA(x, y); //the other code being tested                     }//end y loop                 }//end x loop                 endTime = System.nanoTime();                 deltaTime = endTime - startTime;                 codeATimes[trial] = deltaTime;             }//end codeA Trial          }//end trial loop          long codeASum = 0;         long codeBSum = 0;          for(int x = 0; x < numOfTrials; x++)         {             codeASum += codeATimes[x];             codeBSum += codeBTimes[x];         }          long codeAAvg = codeASum / numOfTrials;         long codeBAvg = codeBSum / numOfTrials;          System.out.println("codeA avg: " + codeAAvg);         System.out.println("codeB avg: " + codeBAvg);      }//end main      private static void codeA(int a, int b)     {         int result = (a + b) & 0xFFFF;          if(result == 0)         {             setZeroFlag(true);         }         else         {             setZeroFlag(false);         }         setSubtFlag(false);         if((((a & 0x0FFF) + (b & 0x0FFF)) & 0x1000) != 0)         {             setHCarryFlag(true);         }         else         {             setHCarryFlag(false);         }     }      private static void codeB(int a, int b)     {         int result = (a + b) & 0xFFFF;          if(result == 0)         {             setZeroFlag(true);         }         else         {             setZeroFlag(false);         }         setSubtFlag(false);          setHCarryFlag((((a & 0x0FFF) + (b & 0x0FFF)) & 0x1000) != 0);     }      private static void setZeroFlag(boolean flag)     {     }     private static void setHCarryFlag(boolean flag)     {     }     private static void setSubtFlag(boolean flag)     {     } }   Please explain why this happens and how to prevent it to give me a realistic benchmark.

How do you write (and run) a correct micro-benchmark in Java?  I'm looking for some code samples and comments illustrating various things to think about.  Example: Should the benchmark measure time/iteration or iterations/time, and why?  Related:


I updated my 18.04 to 18.10 and after rebooting it gets stuck on the boot screen. What can I do to fix this? In case it helps, I have an Nvidia card...

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


I received on my 14.04 version that I can upgrade IT to 14.10. I accepted everything. The updater did download & install files that it needed and asked me to restart the laptop to complete the update. After that, the system shutdown, Lenovo logo appeared on the screen and it got stuck after the logo with a blank black screen and an underline flickering to my left upper screen. What can I do to fix that?  PS: I have tried keeping the Shift while booting to enter in recovery and repair packages, or enter in 'safe mode' even without networking but still no effect. I can't pass that blank screen.


This is the question that has been on my mind lately:  If an object A is moving away from an object B which is presumed stationary by A, then the time observed from the perspective of object B will flow (if you will) faster than the time on the object A, correct?   However in the same way according to my understanding, if   the view points are reversed, then the same effect is to take place from the perspective of the observer in the Object A towards object B. From perspective of observer A (granted there is no point of any observable reference besides object B, object B is moving away and object A is stationary. In which case the time dialation applicable to A and the same effect applicable to B effectively cancel each other out.    Would this be an accurate assumption?   And if later A or B or both A and B reversed their direction and met, would the time lapsed in each of their measurement be equal to the time either of them have spent in apart and therefore be of equal duration relative to both A and B?

Suppose we have two twins travelling away from each other, each twin moving at some speed $v$:    Twin $A$ observes twin $B$’s time to be dilated so his clock runs faster than twin $B$’s clock. But twin $B$ observes twin $A$’s time to be dilated so his clock runs faster than twin $A$’s clock. Each twin thinks their clock is running faster. How can this be? Isn’t this a paradox?


There are    around about getting Ubuntu LTS working with Nvidia 960M cards. Given that there's no definitive answer, I want to offer the following: after testing several distros, Knoppix and Kali both worked without any problems.   So, my questions:    What is different about Ubuntu that Nvidia drivers don't work out of the box? More importantly, is there an easy way (for an end user) to import whatever's working into Ubuntu 16.04?   Edit: Here's what I tried:   Purged nvidia-* and reinstalled 364 drivers. Got login loop, followed answers  (chown, chmod, rm .Xauthority, and  /tmp) Reinstalled xorg and unity. Went to  and found the  version that works with my card (opted for the Long lived branch). Purged nvidia* (no dash, following a tip in a comment), and reinstalled 367 drivers. Purged nvidia*, reinstalled 370 drivers. Currently stuck at login loop, after following instructions from 2.

I installed or upgraded to Ubuntu 16.04, but I'm having some problems with my graphics card.   The display is blank The display flickers Items on the screen do not display correctly Certain programs complain of graphics issues The computer boots to low-graphics mode Your specific issue may not be here, but try the solutions described in the answers anyway.   This question is very broad, but each one of these issues likely has one solution.    If you are experiencing a login loop, check the last part of my answer.    If you experience one of the listed issues and have your own solution (mine didn't work, or there's a faster way), feel free to post another POLITE answer, describing your problem and how you fixed it.    Those attempting to install Ubuntu, please refer to the section titled: If you are unable to enter a TTY or are trying to install Ubuntu.


I am writing a memoir in latex. I have lot of output from Ubuntu terminal and I have tried to put in verbatim, but this is really not pretty. I was wandering if there is a latex tip to put Linux terminal output in latex and make it pretty.

I would like to document work in console while I also think that bitmap images are not the best way to do it. They do not scale well and after all what I am trying to document is text. Therefore I began to wonder whether there is something that could embed text provided into latex formatting which rendered would resemble terminal output.  My intention is to document interaction with a microcontroller using serial line terminal emulator. It typically means single line command followed by a few lines of response.


I'm a bit confused about the whole protected thing in java. If something is protected only the classes within the same package can access it, right?  Should we use protected private attributes in a class? And if so, when?

In Java, are there clear rules on when to use each of access modifiers, namely the default (package private), public, protected and private, while making class and interface and dealing with inheritance?


Hi I am only starting out with Regexs, and am trying to write a regular expression to find string inside curly brackets while keeping curly brackets  Text: "This is a {nice} text to search for a {cool} substring". Answer I want: {nice} and {cool}   I have already looked through the answer here:   This almost does what I want, except that it only returns what's inside the curly brackets. I want to keep the curl brackets.

Unfortunately, despite having tried to learn regex at least one time a year for as many years as I can remember, I always forget as I use them so infrequently. This year my new year's resolution is to not try and learn regex again - So this year to save me from tears I'll give it to Stack Overflow. (Last Christmas remix).  I want to pass in a string in this format {getThis}, and be returned the string getThis. Could anyone be of assistance in helping to stick to my new year's resolution?    Related questions on Stack Overflow:


Let $A$ be a commutative ring with unit and $\mathcal{M}$ the set of all the maximal ideals of $A$.   I need to prove that $$\mathfrak{m}\not \subseteq \bigcup_{\mathfrak{a}\in \mathcal{M}\setminus \{\mathfrak{m}\}} \mathfrak{a}$$ for every $\mathfrak{m}\in \mathcal{M}$.  I get to this statement trying to prove a remark on Neukirch's Algebraic Number Theory that says that if $\mathcal{F}$ is a set of prime ideals of $A$ omitting only finitely many primes, then if $S=(\cup_{\mathfrak{p}\in \mathcal{F}}\mathfrak{p})^c$ we have that the prime ideals of $AS^{-1}$ are of the form $\mathfrak{q}S^{-1}$ where $\mathfrak{q}$ is a prime ideal of $A$ contained in a prime ideal of $\mathcal{F}$ [Page 66]. (I was able to prove that the statement above is equivalent to this)

Suppose $R$ is a Dedekind domain with a infinite number of prime ideals.  Let $P$ be one of the nonzero prime ideals, and let $U$ be the union of all the other prime ideals except $P$.  Is it possible for $P\subset U$?  As a remark, if there were only finitely many prime ideals in $R$, the above situation would not be possible by the "", since $P$ would have to then be contained in one of the other prime ideals, leading to a contradiction.  The discussion at the top of pg. 70 in Neukirch's "Algebraic Number Theory" motivates this question.  Many thanks,  John


I was recently brushing up on my dynamics, when I saw the interpretation of how a car moves in a circular road. Apparently, the car can stay in a circle due to static friction acting inwards. But I don't seem to understand exactly why this force exists and where it originates. What kind of motion causes it to exist?

When a ball moves to the right, friction acts to oppose the motion, in other words, to the left. However, when a car travels around a bend, the friction acts in the perpendicular direction to the car's velocity and provides the centripetal force. I just cannot understand why friction would act in that direction.


I see people running shell scripts by typing ./scriptname. Now this seems to be the default way, since I have seen it so often, however occasionally, but not rare, I see them type sh scriptname. Is it just a matter of preference or is there a more significant difference between ./ and sh ?

This may be a silly question, but I ask it still. If I have declared a shebang  #!/bin/bash    in the beginning of my_shell_script.sh, so do I always have to invoke this script using bash  [my@comp]$bash my_shell_script.sh   or can I use e.g.  [my@comp]$sh my_shell_script.sh   and my script determines the running shell using the shebang? Is it the same happening with ksh shell? I'm using AIX.


People should be treated equally be it rich or be it poor.  Is it a correct sentence. If yes what does it mean???

What does be it mean in this context and what kind of sentence is this? (grammatically)     There is no one in our society who is not ethnocentric to some degree, no matter how liberal and open-minded he or she might claim to be. People will always find some aspect of another culture distasteful, be it practices, a way of treating or relatives, or simply a food that they cannot manage to get down with a smile.


I am doing work for and OS class and for some reason bcc needs a memcpy even though I haven't called it in the code and its unavailable, so I'm rolling my own, however it keeps segfaulting `  void memcpy( void* destination, void* source, size_t bytes ) {         size_t i = 0;         char* destination__ = ( char* ) destination;         char* source__ = ( char* ) source;         if( !( destination__ == source__ ) )         {                 for( ; i < bytes; ++i )                         destination__[ i ] = source__[ i ];         } }   It seems to segfault and I am not sure why, it does fine when things are malloced but not for something like the following.  `  char* foo = "Hello"; char* bar = "Goodbye"; memcpy( bar, foo, 5 );   I have a feeling this is because foo and bar are likely global data, and it has something to do with that but Im not sure. I wouldent be asking except for the fact that I have found other implementations  are  same/ online  It crashes when compiled with regular ol' gcc which Im using to validate outside the OS Im building that has no diagnostics. Im confused as to why this is happening.

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


It's from the movie "The Mask"  Situation: Someone has robbed the bank where Stanley Ipkiss works.  Stanley's boss reprimands Stanley for being late: We have a crisis here, and you stroll in an hour late?  I would have said that sentence either in Present continuous or in Present Perfect.  Self-made: We have a crisis here, and you are strolling/have strolled in an hour late?  I've read in one of my grammar books that sometimes we use Present Simple in narratives and anecdotes to highlight an event.   Is that the reason the speaker used Present Simple instead of Present Perfect/Present Continuous in the original sentence?  Will it be incorrect if I say that sentence in Present Perfect or Present Continuous?    Many thanks in advance.

Non-native speakers often get confused about what the various tenses  and aspects mean in English. With input from some of the folk here I've put together a diagram that I hope will provide some clarity on the matter.  I offer it as the first answer to this question. Consider it a living document. Input is welcome, and good suggestions will be  incorporated into the diagram.    Nota bene: What this is not is a discussion of whether there are  more than two tenses in English. , to which this question is not intended to supply arguments one way or the other.  Here, the aim is to provide an overview of what constructions English-speaking people use for conveying information about actions referring to past, present, and future, and to provide it first and foremost to precisely the people who are likely to use "tense" as a catch-all term in their search, rather than to linguists who know better.  Breaking News There is now an excellent ELU blog article titled  . It is highly recommended reading.


So, i have this code:  \begin{align} S(t+\Delta) &= S(t)-\beta S(t)I(t)\Delta + \phi R(t) \Delta \label{S}\\ I(t+\Delta) &= I(t) + \beta S(t)I(t) \Delta - \gamma I(t) \Delta \label{I}\\ R(t+\Delta) &= R(t) + \gamma I(t)\Delta - \phi R(t)\Delta \label{R} \end{align}   I want this with the numbering after every line (i already have that); but i want an '{' in front of the three lines. Is that possible?

I have the following code  \begin{align} s'(t) &= -\beta s(t) i(t)\\ i'(t) &= \beta s(t) i(t) - \gamma i(t)\\ r'(t) &= \gamma i(t), \end{align}   and I want to enclose this with a bracket like a case, but maintaining the numbered equations.


Beginner here, but for the life of me I couldn't find an answer to this question after searching and trying to figure it out for myself.  I have a very simple app calculating tips, and I'm trying to stop the app crashing when only a decimal place is put into the editText.  public void calculate() {         float result = 0.0f;         float totalBillResult;          if(!enteredAmount.getText().toString().equals("")) {             NumberFormat numberFormat = NumberFormat.getCurrencyInstance(Locale.getDefault());              if(!enteredAmount.getText().toString().equals(".")){                 Toast.makeText(MainActivity.this, "Please enter a bill amount", Toast.LENGTH_SHORT);             }              enteredBillFloat = Float.parseFloat(enteredAmount.getText().toString());             result = enteredBillFloat*seekBarPercent /100;             calculatedTip.setText("Your tip will be " + String.valueOf(numberFormat.format(result)));             totalBillResult = enteredBillFloat+result;             totalBill.setText("Total bill: " + String.valueOf(numberFormat.format(totalBillResult)));          }else {             Toast.makeText(MainActivity.this, "Please enter a bill amount", Toast.LENGTH_LONG).show();         }   I have tried putting another if statement within the above text to get another toast to show if only a decimal is inputted, and while it doesn't cause any errors it also doesn't do anything, and the app just shuts down when I click to calculate.    if(enteredAmount.getText().toString() == (".")) {             calculatedTip.setText("Please enter a number.");         }   I have also tried putting this in the main body of the code to no avail. The logcat is telling me its a NumberFormatException, but after reading this:  that was on another post I am none the wiser on how to fix this.  Any ideas would be appreciated, and I will edit to add more code if needed Thanks

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


Let $a>1$. If someone could give me an extended prove of that result using only sequence sequences, I would really appreciate it. Thanks in advance.

How do I show that $\ln(x) = \lim_{n\to\infty} n (x^{1/n} - 1)$?  I ran into this identity on . I haven't been able to find any proof online and my efforts to get from $\ln(x) := \int_1^x \frac{\mathrm dt}t$ to that limit have been a failure.


I'm trying to find a solution for a programme which I'm writing. The problem occurs even though I tried to prevent it and I don't seem to be able to find a mistake. This is the ''problematic'' part of my code:   if (this.s != null) {         if (s.s != null && s.s.sta.length != 0) {             for (int n = x; n < s.s.sta.length + x; n++) {                     this.sos[n] = s.s.sta[n-x];             }             x = x + s.s.sta.length;         } }   I have an array STA which I'm using and a method which gives me the ''s'' neighbour of an object, so s.s is a neighbour of a neighbour.. What I'm trying to do is copy the objects from more than one specific neighbour into one array with many different if sentences. This one is an example but it doesn't work.  Thank you and I really hope I get some info because I'm completely lost.

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?


xampp (on Windows) is working when I have an index.html or index.php file. I am using .php5 as an extension for new files in the project, and would like to use index.php5 for consistency. It is not a big deal, but my syntax highlighter is set up to color .php files differently, so I am reminded that they are older.  Can I configure xampp to use index.php5?  This is not a duplicate of the other question. The other question is about parsing and running .php5 files in general. This is not a problem on localhost and it is not a problem on any of servers I have running on goDaddy, rackspace and bluehost. The problem is specific to index.php5 - it parses and runs properly when the full name is typed in, but it is not recognized as the default when no file name is entered.  Can I configure xampp to DEFAULT to index.php5 given that php5 is working?

I've installed XAMPP Apache server and put my website into htdocs. I've started Apache server. On my website I've got files with extension PHP and with extension PHP5.The difference is that when I type in into browser localhost/file.php - I see a parsed website.  But when I type localhost/file.php5 (i have this file on server), than browser asks me if I want to download or open this file. And if I choose open than I see PHP code of file.php5!  I've looked into configuration, so:   I dont have htaccess file PHPINFO() shows PHP 5 c:\xampp\apache\conf\extra\httpd-xampp is included into configuration and has this on the beginning:  AddType application/x-httpd-php-source .phps  AddType application/x-httpd-php .php .php5 .php4 .php3 .phtml .phpt   I've tried also to put:  AddHandler php5-script .php5 AddType text/html .php5   Into httpd.conf, but it does not work for me (no changes).  Could you please help me fixing it? I would like to have php5 and php extension files to be opened with php5 parser.


Statement: Given a connected graph with all edges coloured in one of two colours (red and black), so that for each vertex the number of incident red edges is equal to the number of black edges.  Proof: there is a color-alternating path between any pair of vertexes.  I had some thoughts on this problem in context of Euler cycle (I can even prove it in the other direction), also have found such theorem:  Theorem (2 colors): A 2-edge colored graph has an alternating Euler cycle if and only if the red degree=blue degree for every vertex  May be someone knows how to prove it ?

We have connected undirected graph with colored edges in two way (green or blue). And also each vertex have the same number of green and blue edges. How to prove that there are alternate colored (green-blue) path between any two nodes?


Ok, let's leave the debate of whether friendship breaks encapsulation, and actually try elegantly come up with a coherent design. It is a two fold function:  1) General question on how to implement:     public class A     {       friend class B;    }   2) Why do I need this functionality? Some of my classes implement Serializable interface. However, I want to make Serializable methods protected in the Derived class so that I don't expose them to a client (as well as in the documentation -- javadoc). However, internal classes should be able to access them. What is the General way to solve this problem in java?  Note: I am using friendship as defined in the current C++ standard.  Thanks

I would like to be able to write a Java class in one package which can access non-public methods of a class in another package without having to make it a subclass of the other class. Is this possible?


Mixamo does a decent job when I need to rig something fast but the fact that all material are gone "compensates" the saved time, forcing me to do it again

I used node textures in a mesh I exported to .FBX.  I then imported it into Unreal Engine 4 and it didn't import any textures; I clicked the Upload Textures option in Unreal Engine.  Is there something I'm doing wrong or is it Blender?


I'm new to Java and am trying to learn how to read/write to excel using the Apache POI. As of now, I am just trying to write a new excel file, but even after throwing  the IO exception, I am getting a java.lang.ClassNotFoundException: org.apache.xmlbeans.XmlException exception.  Here is my code:  package ExcelDemo;  import org.apache.poi.xssf.usermodel.XSSFWorkbook;  import java.io.File; import java.io.FileOutputStream; import java.io.IOException;  public class Demo {      public static void main (String[]args) throws IOException {         try {             XSSFWorkbook workbook = new XSSFWorkbook();             FileOutputStream out = new FileOutputStream(new File("C:/Users/colin/IdeaProjects/FinancialIndependence/src/ExcelDemo.xlsx"));             workbook.write(out);             out.close();         }         catch(Exception e){             System.out.println(e);         }          System.out.println("Excel file outputted");     } }   Here is the error I am getting:  Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/xmlbeans/XmlException     at ExcelDemo.Demo.main(Demo.java:13) Caused by: java.lang.ClassNotFoundException: org.apache.xmlbeans.XmlException     at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)     at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:190)     at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)     ... 1 more  Process finished with exit code 1

I am getting a NoClassDefFoundError when I run my Java application.  What is typically the cause of this?


I've tried to display UTF-8 in the win7 cmd. Currently, I'm using the standard font because as I see with the mysql.exe, it works fine with the characters I'm working with (currently the german umlauts "ßäöüÄÖÜ"). Also, with another font, the same characters appear.  But the output of my PHP script displays garbage, e.g. 'ÃŸ' for 'ß'. When I pipe the output into a file and open it up with Notepad++, it says the encoding is UTF-8. In php.ini I set UTF-8 as the encoding as well as in the connection to the mySQL database, and in the database itself UTF-8, too.  In CMD I tried so far to set the code page to 65001, but nothing changes.  edit: my PHP script is saved as UTF-8 as well  It seems with latin1, my desired characters can be displayed too and actually it works. But there has to be a way to do it in UTF-8? I can't convert everything to latin1

We have a project in Team Foundation Server (TFS) that has a non-English character (š) in it. When trying to script a few build-related things we've stumbled upon a problem - we can't pass the š letter to the command-line tools. The command prompt or what not else messes it up, and the tf.exe utility can't find the specified project.  I've tried different formats for the .bat file (ANSI, UTF-8 with and without ) as well as scripting it in JavaScript (which is Unicode inherently) - but no luck. How do I execute a program and pass it a Unicode command line?


I tried this, but it is undefined:  alert($(ev.relatedTarget).attr('name'));   I have a combobox (textbox and a button), I don't want the code to continue processing if the input goes to its partner control(button). I want to detect from textbox blur that it is leaving the whole combobox not just the textbox. Textbox's blur will naturally trigger when I click its partner button. The only ideal logic I can think of is to detect from textbox's blur that the focus destination is not its partner button, if the relatedTarget is its partner button don't continue processing.

Suppose I attach an blur function to an HTML input box like this:  <input id="myInput" onblur="function() { ... }"></input>   Is there a way to get the ID of the element which caused the blur event to fire (the element which was clicked) inside the function? How?  For example, suppose I have a span like this:  Hello World   If I click the span right after the input element has focus, the input element will lose its focus. How does the function know that it was mySpan that was clicked?  PS: If the onclick event of the span would occur before the onblur event of the input element my problem would be solved, because I could set some status value indicating a specific element had been clicked.  PPS: The background of this problem is that I want to trigger an AJAX autocompleter control externally (from a clickable element) to show its suggestions, without the suggestions disappearing immediately because of the blur event on the input element. So I want to check in the blur function if one specific element has been clicked, and if so, ignore the blur event.


This started happening today for absolutely no reason. Worked perfectly last week. I didn't touch the machine.  I have an issue described  and need to downgrade in order to be able to upgrade. Currently I'm not able to enter the shell as it exits with error #4   need to upgrade database admin with pdfile version 4.22, new version: 4.5  If I run it with --upgrade I get:  ERROR: error: exception cloning object in admin.system.users system.users entry must have either a 'pwd' field or a 'userSource' field, but not both obj:{ _id: "nod$ exception in initAndListen: 2 system.users entry must have either a 'pwd' field or a 'userSource' field, but not both, terminating   I'm trying sudo apt-get install mongodb-10gen=2.2.7but it doesn't work because that version is missing - I dont know if there is any way to install legacy versions?  Can anyone direct me to a command I can use to install version 2.2.7?

This started happening today for absolutely no reason. Worked perfectly last week. I didn't touch the machine.  I have an issue described  and need to downgrade in order to be able to upgrade. Currently I'm not able to enter the shell as it exits with error #4   need to upgrade database admin with pdfile version 4.22, new version: 4.5  If I run it with --upgrade I get:  ERROR: error: exception cloning object in admin.system.users system.users entry must have either a 'pwd' field or a 'userSource' field, but not both obj:{ _id: "nod$ exception in initAndListen: 2 system.users entry must have either a 'pwd' field or a 'userSource' field, but not both, terminating   I'm trying sudo apt-get install mongodb-10gen=2.2.10but it doesn't work.  Can anyone direct me to a command I can use to install version 2.2.10?


In the Harry Potter series Harry's parents go into hiding by using a Fidelus Charm which needs a secret keeper. So they chose Peter Pettigrew as their secret keeper and were betrayed. Why didn't they make each other their secret keeper? James could have made Lily secret keeper (of his and Harry's secret) and Lily could have made James (of her and Harry's secret) their secret keeper. So there wouldn't have been any chance of third person betraying them.

Why wasn't James Potter his own Secret Keeper? The whole thing came about because Potters chose the wrong Secret Keeper (who betrayed them) for the Fidelius Charm on their house. Why didn't James just make himself a Secret Keeper? We know that it’s possible from Deathly Hallows: (Bill and Arthur Weasley are their own Secret Keepers).  “I’ve been getting them all out of the Burrow,” Bill explained. “Moved them to Muriel’s. The Death Eaters know Ron’s with you now, they’re bound to target the family – don’t apologize,” he added at the sight of Harry’s expression. “It was always a matter of time, Dad’s been saying so for months. We’re the biggest blood traitor family there is.” “How are they protected?” asked Harry. “Fidelius Charm. Dad’s Secret-Keeper. And we’ve done it on this cottage too; I’m Secret-Keeper here."


I just would like to ask when can i reapply for visiting visa in the Netherlands? I have been there last December 19,2016 til February 18,2017. I lately just read about "90 days in 180 days period". What does that mean? I checked my recent visa and saw the dates from December 17,2016 til April 1, 2017( 105 days). Can i apply for reentry visa this May? I hope you can help me out. Thanks in advance!

I have searched the web a lot and could not find an answer that fits my situation. Here are two links that are quite contradictory:       My situation:  I've visited Portugal in December 2012 for 29 days on a Schengen visa valid from December 1st, 2012 to February 1st, 2013 for research purposes (I am a Ph.D. student). I want to visit Sweden from February 10th, 2013 to May 10th, 2013 (89 days). I have applied for a Schengen visa again (for research). How will the 90/180 rule work in my situation?


I am working with some gstreamer based application and some other streaming stuff and I came to some confusion: What is difference between libav and ffmpeg?  I found no explanation what are they and how they differ. Even more one have tool called ffmpeg while other does have the same thing too. Also even those project logos are the same. And to make matters worse even external application who uses them misnames them, mix them (gstreamer-0.10 refers to ffmpeg, while gstreamer-1.0 refers to libav).  Is there easy way to find out which library is really needed and used by application? Is there any technical (non political software licensing nonsense) difference why projects split away and I should be aware of when I should work with them?  Update: Someone in comments put the links to questions related to history of both libraries and usefull info. However I doubt that my question is exact duplicate:   I am asking method itself to detect libraries. List or something like that, caveats or even hints how libraries work different one from another, not opinion which is better, neither how licensing communities differ one from another.

From what I've seen it looks to me like Libav's avconv is thought to become a successor of ffmpeg — is that correct?   If that's true, why is that so? What exactly is libav doing better and why would I want to choose it over ffmpeg?   I came to this "issue" while installing Ubuntu 12.04.1 LTS in a VM and when I've installed ffmpeg it came up with a message telling mit ffmpeg is deprecated and I first thought "wtf?".  If I use avconvWill I be able to migrate my scripts depending on ffmpeg more or less easy to libav? I'm mostly using it for writing meta data and doing audio conversion (wav, flac, vorbis, mp3, aac).


I have two external hard discs on an OpenSUSE 13.1 system.   On one I have created a partition structure:   An encrypted LVM partition (LUKS) Several volumes (10) on this LVM partition, some formatted with xfs, some with ext4.    sdf                              8:80   0   5,5T  0 disk   └─sdf1                           8:81   0   5,5T  0 part     └─extern-2-crypt             253:5    0   5,5T  0 crypt      ├─extern--2-nelson--home   253:10   0     8G  0 lvm   /extern/nelson/home     ├─extern--2-lucien--boot   253:11   0   300M  0 lvm   /extern/lucien/boot     ├─extern--2-nelson--root   253:12   0  11,5G  0 lvm   /extern/nelson/root     ├─extern--2-nelson--space  253:13   0  90,1G  0 lvm   /extern/nelson/space     ├─extern--2-lucien--backup 253:14   0   400G  0 lvm   /extern/lucien/backup     ├─extern--2-lucien--home   253:15   0    20G  0 lvm   /extern/lucien/home     ├─extern--2-lucien--raid   253:16   0   3,5T  0 lvm   /extern/lucien/raid     ├─extern--2-lucien--root   253:17   0   8,5G  0 lvm   /extern/lucien/root     └─extern--2-lucien--space  253:18   0    30G  0 lvm   /extern/lucien/space    How can I replicate this structure easily including the LVM config from one disc to the other (with only one disc running at the same time)?   I know of sgdisk (8) and parted (mentioned in ), but that covers only the partition, not the LUKS information and certainly not the LVM config.

I want to take a backup of the whole partition layout of a hard drive, including logical drives, so that I can restore that layout to another disk. I do not want to copy the contents of the partitions, only the layout. For the primary and extended partitions, it's easy:  dd if=/dev/sda of=partitiontable.bin bs=1 skip=446 count=64 # backup dd if=partitiontable.bin of=/dev/sda bs=1 seek=446 count=64 # restore   But when it comes to the layout of the logical partitions, I wonder if there exists among the standard tools a similar way of saving the layout? I guess the main problem is finding the offsets to the locations of the EBRs, because with that, dd will do the rest. Keep in mind I need to be able to put everything back to a (possibly) blank disk and thereby restore the same layout. Using partitioning tools like fdisk or parted is fine, but I must be able to automate their use (scripting) and they should not depend on any X-related packages -- command line only.  My backup plan is doing it manually in a little python script using the struct module, but I rather hoped there was an easier way.


Phantasmal Force      2nd-level Illusion      Casting Time: 1 action      Range: 60 feet   If I were to cast this spell, and either I or the target otherwise become greater than 60 feet away from each other during the duration, would the spell fail/end?  There is precedent in other spells like Witch Bolt which specifically says the spell ends if the target is outside the spell's range, but Phantasmal Force never specifies such a condition.

Does going outside the range of the spell or breaking line of sight between the caster and target break concentration or otherwise affect control over the spell?  For example, a Heat Metal spell has a range of 60 ft. If I cast the Heat Metal spell on a an armored foe, and that foe runs outside the range of the spell (60 ft), or around the corner, does that break concentration and end the spell? Heat Metal also allows you to use a bonus action to cause the 2d8 of damage — would exercising that option be prevented by being out of range or line of sight?


Using the axiom of choice, or more directly, the statement that every linearly independent set of vectors in a vector space may be extended to a basis, it is easy to prove that every short exact sequence of vector spaces splits.  Is the converse also true? Over ZF, does the splitting of each short exact sequence of vector space suffice to prove that every vector space has a basis?  One thing I tried was the following: suppose that $V$ is a vector space over $k$, and let $k[V]$ be the vector space freely generated by the elements of $V$, and let $k[V] \to V$ be the "projection". Then you get a section $V \to k[V]$... but it doesn't seem there's any way to guarantee the image of the section contains any standard basis vectors.

Let say we live in the category of vector spaces over $\mathbb{R}$ or $\mathbb{C}.$ Here are three sentences:   Axiom of choice Every vector space has a base. For every vector space $V$ and its subspace $E\subset V$ there is a subspace $F\subset V$ such that $V=E\oplus F.$    I know how to prove that (1)->(2)->(3). How about the inverese? Do (2)->(1) and (3)->(2) hold?  If this is not the case, then is there some weaker version of AC which imply (3)?


Statement:  Let $n$ and $m$ be two irrational numbers. Then $n^m$ is always irrational.  I think this statement is correct, otherwise can someone give me a counterexample?  Thanks!

Can an irrational number raised to an irrational power be rational?  If it can be rational, how can one prove it?


$$\int \sqrt{1+x^2}\,dx$$  I've tried some step-by-step calculators, but what they give is way beyond my level. Is there any "simple" way to solve this?

$$\int\sqrt{x^2+1}dx$$ I've been attempting this problem for days and I've made very little progress. I understand that I should substitute $x=\tan(x)$ and $dx=\sec^2(x)dx$ but beyond that I am very much lost.


I have two files:  file 1:  a,txt1,v1 b,txt2,v2 c,txt3,v1 d,txt4,v2   file2:  a,txt5,v2 b,txt6,v1 xc,txt7,v1 xd,txt8,v2   I want to refine the files. I only need the lines where the 1st column in file1 has match in file2.   The new file1 should contain:  a,txt1,v1 b,txt2,v2   Similarly, file2 should be refined to contain only lines where there is a match in the 1st column with file1. So file2 should be:  a,txt5,v2 b,txt6,v1

I use Ubuntu 18 and have little experience with Linux commands. I have two files:  file 1:  a,txt1,v1 b,txt2,v2 c,txt3,v1 d,txt4,v2   file2:  a,txt5,v2 b,txt6,v1 c,txt7,v1 d,txt8,v2   I want to print the 1st and 3rd column values where the the 1st column value is identical and the 3rd column value has changed from v1 to v2. So my expected output should be:  a   The second query is for the 3rd column values that has changed from v2 to v1. So my expected outcome:  b


I have a problem displaying "€" in my html...   My database field has collation "utf8_general_ci" I fetch the data like that into an javascript variable:  $query = mysqli_query($con, "SELECT * FROM Table WHERE Id = '1'"); $data = mysqli_fetch_assoc($query);  $data = json_encode(utf8_encode(($data["Field"])));    As I want to echo $data... I get Umlauts see "ÄüÖü" and other chars like " ', #@&" etc.  BUT I DON'T SEE THE € SIGN..... it get's displayed as a ? ( Not that in a rectangle... just a normal ?)  Can anyone help please?  Btw, that's my header:  header("Content-Type: text/html; charset=utf-8");

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


I just made an edit and saved it without giving it an edit summary. The default summary was      added 24 characters in body   I made another edit to the same post within 5 minutes, this time changing the automatic edit summary, however, when I viewed the edit, the original automatic summary remained.  I suggest that we be allowed to edit the summary while we're within 5 minutes of posting the edit.  It has been suggested that users can make two edits to change the summary: the first by making a superfluous change, the second by undoing the change and changing the summary at the same time. This is counterintuitive and surprising behaviour. A user only has 5 minutes to change an edit before it becomes a new edit, and in that period they should be able to do anything they could have done on the first edit.  This feature was first suggested in early 2011 and was very popular, yet was never done. If the reason it hasn't been implemented is to avoid trivial edits, then the workaround (which didn't work for me) simply doubles the number of trivial edits needed to get the job done.

It often occurs to me to add an edit summary to a question-edit immediately after submitting the edit, especially if the changes aren't obvious (formatting etc.). So I:   Click "edit" again. Fill in the summary Click on "Save Edits".   The 'edit' (no actual change has been made to the title/body/tags)  is accepted, but the summary doesn't show up, i.e. it is silently rejected.   I don't think it should work this way because the summary has been added by the original editor within the original edit's edit-window. In fact if I remember correctly, it to used to work as expected earlier; so perhaps this is a recent change.


I have recently upgraded my PC with a GTX 1080 Ti graphics card, and an i7 7700k Kaby Lake CPU, now however, I can't boot at all into my Linux partition, nor can I even run a live CD to customize the install to use non-free drivers. I tried on another PC to make sure my media wasn't going bad, and I was able to boot into Linux successfully and run the Live CD. Is there anyway to boot a live CD on this hardware and install Linux? I do also have a DisplayPort out on my motherboard for iGPU if that is necessary.

Today I tried several times to install Ubuntu but I have some GPU problems.  I have a bootable stick. When I boot in UEFI mode all its normal but the installer isn't able to install the boot loader.  When I boot in leagacy mode I'm able to install Ubuntu but only when I unplug my GPU GTX 1070.  When I don't do that, I get an this initialization error from the installer:  3.021954] nouveau 0000:01:00.0: unknown chipset (134000a1)   I installed Ubuntu normally without the GPU. I installed the drivers, rebooted, shut down, pluggeed in the GPU and tried to boot but it got stuck at:  /dev/mapper/isw_bdifbbjbai_Raid0p3: clean, 191449/8855552 files, 1677252/34500448 blocks   What should I do? When I unplug the GPU I can boot easily, but I need my GPU! :D  My PC has a GTX 1070 GPU, i7 4790K CPU, and two hard drives:   250 GB M.2 SSD, which contains Windows 10 and its boot loader. 2 TB RAID-0 WD, with 1,85 TB for Windows 10 files and 150GB where I installed Ubuntu and its boot loader.


I use a quite complicated way to make my citation, as I need to use the same citation as a reference in different places in my text.   Now I got the correct way of showing the citation in footnote, but each citation has 2 numbers, and the number of the citation is not in order (the one with squared brackets). It comes out like   1[3], 2[1], 3[4], 4[2]    I want them show as (this problem has been solved with sorting=none)  [1],[2],[3],[4]   And how to remove the number 1 before [1]?  Is that possible to set the referenced citation also as superscript inside the text? In order to keep reference citation work, I keep the script for footpartcite and partcite.  Thank you!  \documentclass[a4paper, 12pt, headsepline,DIV=12,twoside]{report} \usepackage[english]{babel} \usepackage{mathptmx}  \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{parskip} \usepackage{filecontents} \usepackage[backend=bibtex,style=numeric,natbib=true]{biblatex} \usepackage{textcomp} \usepackage{csquotes}  \begin{filecontents}{\jobname.bib} @Electronic{unintentional, Title                    = {Accidents or Unintentional Injuries}, Author                   = {{National Center for Health Statistics}}, URL                      = {http://www.cdc.gov/nchs/fastats/accidental-  injury.htm}, urldate                  = {2016-08-10},} @Book{HP, Title                    = {Harry Potter and the Philosopher's Stone}, Author                   = {{Rowling,J. K. }}, Date                     = {1997}} @Misc{ASH, Title                    = {Automotive Safety Handbook}, Author                   = {{Seiffert, Ulrich; Wech, Lothar}}, Date                     = {2003}, Editor                   = {SAE International}, Note                     = {pp. 91, 96, 97}} @Electronic{CrashStatistic, Title                    = {Annual Global Road Crash Statistics}, Author                   = {{Association for Safe International Road Travel}}, Date                     = {2016-07-16}, Url                      = {https://asirt.org/initiatives/informing-road-users/road-safety-facts/road-crash-statistics}} \end{filecontents}  \usepackage{xcolor}  \usepackage{hyperref} \hypersetup{colorlinks,linkcolor={black},citecolor={blue!50!black}}  \DeclareCiteCommand{\footpartcite}[\mkbibfootnote] {\usebibmacro{prenote}} {\usebibmacro{citeindex}% \mkbibbrackets{\usebibmacro{cite}}% \setunit{\addnbspace} \printnames{labelname}% \setunit{\labelnamepunct} \printfield[citetitle]{title}}% {\addsemicolon\space} {\usebibmacro{postnote}}  \DeclareMultiCiteCommand{\footpartcites}[\mkbibfootnote]{\footpartcite}   {\addsemicolon\space}  \DeclareCiteCommand{\partcite} {\usebibmacro{prenote}} {\usebibmacro{citeindex}% \mkbibbrackets{\usebibmacro{cite}}% \setunit{\addnbspace} \printnames{labelname}% \setunit{\labelnamepunct} \printfield[citetitle]{title}% {\addsemicolon\space} {\usebibmacro{postnote}} \DeclareMultiCiteCommand{\partcites}{\partcite}{\addsemicolon\space}  \addbibresource{\jobname.bib} \begin{document} Each citation has two numbers.\footpartcite{unintentional} And the order of citation is not correct. \ref{ftn:unintentional}  I dont know how to put unsrtnat style inside my preamble, because the system said it´s not existing.\footnote{\label{ftn:unintentional}\partcite{unintentional}}  And I have tried to define natbib separately \ref{ftn:unintentional} But the system says I have already defined it with usepackage {biblatex}\footnote{\label{ftn:HP}\partcite{HP}}  The citation number inside text is not correct,\footpartcite{CrashStatistic} because only 4 citations have been used here \footpartcite{ASH}  Does anyone know how to solve them?\ref{ftn:HP}   \printbibliography \end{document}

I have read the posts related to bibliography topic, but they cant really help me. I hope someone can really help me for these questions, as I have to hand it in on next monday...  I have also written all my questions in my MWE, so if you want to, you can read my script directly to save sometime!    In order to keep reference citation work, I keep the script for footpartcite, partcite, and footnote.  How to list the bibliography alphabetically? Now I got the correct way of showing the citation in footnote, but each citation has 2 numbers, it comes out like   1[1], 2[2], 3[3], 4[4]    I want it show as  [1],[2],[3],[4]   how to remove the number 1 before [1]?   I have used \footnoteref instead of \ref, because \ref doesnt appear as superscript in the text, if you know how to set it as a superscript of the text, then it will be even better, because it can be written inside a caption directly!  Solution for single question is also really appreciated! Thank you very much!  \documentclass[a4paper, 12pt, headsepline, DIV=12,twoside]{report} \usepackage[english]{babel} \usepackage{mathptmx}  \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{parskip} \usepackage{filecontents} \usepackage[backend=bibtex,style=numeric,sorting=none,natbib=true]{biblatex} \usepackage{textcomp} \usepackage{graphicx} \usepackage{csquotes}  \begin{filecontents}{\jobname.bib} @Electronic{unintentional, Title                    = {Accidents or Unintentional Injuries}, Author                   = {{National Center for Health Statistics}}, URL                      = {http://www.cdc.gov/nchs/fastats/accidental-   injury.htm}, urldate                  = {2016-08-10},}  @Book{HP,  Title                    = {Harry Potter and the Philosopher's Stone},  Author                   = {{Rowling,J. K. }},   Date                     = {1997}} @Misc{ASH, Title                    = {Automotive Safety Handbook}, Author                   = {{Seiffert, Ulrich; Wech, Lothar}}, Date                     = {2003}, Editor                   = {SAE International}, Note                     = {pp. 91, 96, 97}} \end{filecontents}   \DeclareCiteCommand{\footpartcite}[\mkbibfootnote] {\usebibmacro{prenote}} {\usebibmacro{citeindex}% \mkbibbrackets{\usebibmacro{cite}}% \setunit{\addnbspace} \printnames{labelname}% \setunit{\labelnamepunct} \printfield[citetitle]{title}}% {\addsemicolon\space} {\usebibmacro{postnote}}  \DeclareMultiCiteCommand{\footpartcites}[\mkbibfootnote]{\footpartcite}   {\addsemicolon\space}  \DeclareCiteCommand{\partcite}  {\usebibmacro{prenote}} {\usebibmacro{citeindex}%  \mkbibbrackets{\usebibmacro{cite}}%  \setunit{\addnbspace}  \printnames{labelname}% \setunit{\labelnamepunct}  \printfield[citetitle]{title}%  \newunit  \printfield{year}} {\addsemicolon\space} {\usebibmacro{postnote}} \DeclareMultiCiteCommand{\partcites}{\partcite}{\addsemicolon\space}  \usepackage{remreset} \makeatletter  \@removefromreset{footnote}{chapter} \newcommand\footnoteref[1]{\protected@xdef\@thefnmark{\ref{#1}}  \@footnotemark}  \makeatother  \addbibresource{\jobname.bib} \begin{document}  Q1: Each citation has two numbers. \footnoteref{ftn:unintentional} How to remove the number in front of the squared brackets. \footnoteref{ftn:unintentional}  Q2: know how to list the bibliography alphabetically. \footnote{\label{ftn:unintentional}\partcite{unintentional}}  Q3: how to put a footnoteref inside of a caption? because if I put it inside a caption of a table or figure, it will show error, but if I put it outside the caption bracket, \footpartcite{ASH} the footnoteref will show in the next line rather than as superscript of the caption.  \footnote{\label{ftn:HP}\partcite{HP}}   \begin{figure}[h] \includegraphics[width=\textwidth]{example-image-a} \caption{I am a figure}\footnoteref{ftn:HP} \end{figure}  Does anyone know how to solve them? Thank you very much!  \printbibliography \end{document}


In the Wikipedia article for skew symmetric matrixes the following propert is stated: If A is a real skew-symmetric matrix, then I + A is invertible, where I is the identity matrix.  However I haven’t been able to find a proof of this or why it does not apply to complex matrices.     This is different from the one where I - A is invertsble because this is I + A

Let $A\in M_{n\times n}(\mathbb{R})$ be a skew-symmetric  matrix. show that $A-I$ is invertible and $(A-I)^{-1}(A+I)$ is an orthogonal matrix.   $|A-I|=|(A-I)^T|=|-(A+I)|=(-1)^n|A+I|$  I have no clue to solve this problem, I appreciate any help.


Can X11 and Wayland be used at the same time? My Display Server of choice is X11, and I want to use an application that only supports Wayland - would that be possible at all?

Is there's wayland server running as X11 client? Like  but reversed.


"Biweekly" means every two weeks. What's the term for something that happens twice a week?     We need to have _______ meetings until this crisis is over.

We have two words for events occurring in periods of years - biannual meaning twice a year, and biennial meaning once every two years.  However, my colleagues talk about having meetings biweekly. This causes a lot of confusion, since it can mean either once every two weeks or twice a week.  We can use fortnightly to indicate once every two weeks and help disambiguate that way. Are there any other words we could use which could help, particularly words which mean "twice a week"? I'm looking particularly because some of my colleagues speak English only as a second language, and find fortnightly difficult to remember.


I'm php web developer and got stuck with a little problem. I'm Using code-igniter framework. The Problem is that all emails emails are going to junk folder only in outlook case. But in case of gmail, the code is working properly. all emails are going to inbox folder. Is there any security issues between both of them.? Need Suggestions Please. Thanks ab

This is a tricky one and I've always relied on techniques, such as permission-based emails (i.e. only sending to people you have permission to send to) and not using blatantly spamish terminology.  Of late, some of the emails I send out programmatically have started being shuffled into people's spam folder automatically and I'm wondering what I can do about it.  This is despite the fact that these particular emails are not ones that humans would mark as spam, specifically, they are emails that contain license keys that people have paid good money for, so I don't think they're going to consider them spam  I figure this is a big topic in which I am essentially an ignorant simpleton.


Can I invert the D+ and  D- in a USB OTG connection?, would it work? I know that in some protocols like PCIe you can do it, but Im not sure about usbOTG.

I heard that D+ and D- are differential signals, does it matter if I swap them when connecting a USB device to the computer?


I am new to Sharepoint. I am using Sharepoint Designer 2013. Need pointers/sample code to accomplish the below.  I have to 2 custom Lists like below. Ex:  State (Custom list1)  State AP UP MP   City (Custom list2)  City State Desc KNR AP  WL  UP NZB AP SRC MP HZB UP   I have to create a page, where I have to load dropdown values from 1st list. When I selected the value from dropdown, I should get all the selected dropdown value related data from 2nd list in a table/grid, where I have to edit the table and save.

I'm trying to implement cascading drop down for list in SharePoint online  I have 3 different list with name Countries , States, cities.  and the master list Address in which I have Fields Country , State, City.  I'm trying to display Sates for selected country. and City for selected States in SharePoint Online list


I am getting this error. How can I upgrade now?

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?