each time i go to the root and try to change my passwd an error occurs and it says authencation manipulation error or some thing like that.and btw the passwd s match. whoever knows whats happening please help.HOw DO I CHANGE MY PASSWD .
I am logging in to my Ubuntu Server using my username. Once I am logged in I am typing passwd command. Entering a new password but a second after getting following error messages:  passwd: Authentication token manipulation error passwd: password unchanged   What is wrong here? How can I change my password otherwise if I don't have access to that server physically, i.e. I am connecting remotely with ssh using terminal.
Does $\lim_{h\rightarrow 0}\ [f(x+h)-f(x-h)]=0$ imply that $f$ is continuous? How did Stannis's army get north of the wall? If Mance Rayder had to attack Castle Black to use the tunnel to get through the Wall and get out of the north, how did Stannis get his army across the Wall into the north without anyone knowing? If there was another way over the Wall wouldn't the wildings go that way too? Let $S$ and $W$ be subsets of a vector space $V$. Show that if $S$ is a subset of $W$, then $\mathrm{span}(S)$ is a subspace of $\mathrm{span}(W)$ Let $S$ and $W$ be subsets of a vector space $V$. Show that if $S$ is a subset of $W$, then $\mathrm{span}(S)$ is a subspace of $\mathrm{span}(W)$.  Ok I'm finally understanding what each of these things mean.. but I'm running out of ideas on how to actually show it without using arbitrary vector space examples like Rn. Since sets and subspaces are kind of new its hard to figure out how to write correct proofs with them.   I can see how if $V = \mathbb{R}^3$ and $S = \{(1,1,1)\}$ and $W = \{(1,1,1), (1,1,2)\}$ then $\mathrm{span}(S) = R1(line), span(W) = R2(plane)$ and that R1 is a subspace of R2... im just having trouble showing this officially when all vector spaces and sets are completely in general....  I could get as far as writing out $S=(u_1,u_2,\dots,u_n)$, $u_i \in V$ and same with $W$, but I can't really figure out what else to do in this sort of proof. The server version of Ubuntu does not have the  command. How can I add a  (PPA) to the server without this command? Consider this equation :   $$\sqrt{\left( \frac{dy\cdot u\,dt}{L}\right)^2+(dy)^2}=v\,dt,$$  where $t$ varies from $0$ to $T$ , and $y$ varies from $0$ to $L$.  Now how to proceed ?   This equation arises out of following problem :   A cat sitting in a field suddenly sees a standing dog. To save its life, the cat runs away in a straight line with speed $u$. Without any delay, the dog starts with running with constant speed $v&gt;u$ to catch the cat. Initially, $v$ is perpendicular to $u$ and $L$ is the initial separation between the two. If the dog always changes its direction so that it is always heading directly at the cat, find the time the dog takes to catch the cat in terms of $v, u$ and $L$.  See my solution below :   Let initially dog be at $D$ and cat at $C$ and after time $dt$ they are at $D'$ and $C'$ respectively. Dog velocity is always pointing towards cat.  Let $DA = dy, \;AD' = dx$  Let $CC'=udt,\;DD' = vdt$ as interval is very small so $DD'$ can be taken straight line.  Also we have $\frac{DA}{DC}= \frac{AD'}{ CC'}$ using triangle property.  $\frac{dy}{L}= \frac{dx}{udt}\\ dx = \frac{dy.udt}{L}$  $\sqrt{(dx)^2 + (dy)^2} = DD' = vdt \\ \sqrt{(\frac{dy.udt}{L})^2 + (dy)^2} = vdt $  Here $t$ varies from $0-T$, and $y$ varies from $0-L$. Now how to proceed? I understand what the Chinese remainder theorem is. However I am not sure how to apply it to my question. Can someone explain please? Cross referencing between chapters of a thesis Hi I am new to the forum and fairly new to Tex, if I miss anything out please let me know and I will be glad to post it. I am writing up my PhD thesis using Texmaker on a windows system. I have my document organised with a main file and a sub-directory containing chapter 1 to 5. I want to be able to use the labels I created in chapter two for example in the appendix and vice versa. Is there an easy way to do this?   I have tried following the advice of various posts of including the commands \usepackage{xr} and \externaldocument{Chapters/Chapter_2} in the individual chapters but this leads to an error when compiling.   My Preamble is as follows:  \documentclass[12pt,hidelinks,twoside]{report} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[greek,spanish,english]{babel} \usepackage{textgreek} \usepackage[version=3]{mhchem} \usepackage[a4paper,width=150mm,top=25mm,bottom=25mm,bindingoffset=6mm]{geometry} \usepackage{amsmath, amsfonts, pifont, float, color, url} \usepackage[pdftex]{graphicx} \usepackage[style=numeric,backend=biber,sorting=none]{biblatex} \addbibresource{references.bib} \usepackage[pdftex, plainpages=false, pdfpagelabels, bookmarks=true]{hyperref} \usepackage{fancyhdr} \usepackage[center,font={it,small}]{caption}   I then have a section such as this in the main document:  \begin{document} %%... Title page ... \chapter{Theory and Methods} \label{chap:Theory and Methods} \include{Chapters/chapter_2} %%... Other chapters .... \end{document}   In Chapter 2 I have for example a label for a diagram which I may want to reference in other chapters:  \begin{figure}[H] \centering \includegraphics[height=10cm,width=\textwidth]{RF_colour_hi_res.pdf} \caption{Random Forest} \label{fig:2.1 Random Forest} \end{figure}   How can I have this label show up in other chapters after I type \ref ?  Many thanks in advance.  If any other information is required please let me know.   This has been answered in the comments although the references do not appear in the auto complete if they are copied and pasted in they still work. The disk that contains Ubuntu on my computer is 115GB in size.  When the disk was 114.7GBfull.  I started deleting some files here and there to free up around 5GB.  But I noticed the disk was 114GB filled again. I thought it was some cache or swap thingy so didn't give it much thought and went ahead and freed around 40GBby shifting some media files out of the disk.  I have a notification in an hour or so that the disk is full yet again!! 40GB!!! All gone!  So I debugged the problem down to the /var/log/syslog file which was initially definitely less than 20GB. I know this because /var folder was 17GB before I cleared the memory.  /var/log/syslog file is currently 55.9GB!  Could someone be so gracious to explain this anomaly? Is this a bug? Or am I affected with some malware or virus? Word for a person who continually tries to teach you when it's not necessary I've experienced this way too many times, and the best example I can give is a person who treats you like you have no idea how to do X and who keeps teaching you how to do it. I feel handicapped. Take for example how to play a card game. You know how to play the game because you've played it 5 times. However, there is a person always insists on explaining the game to you - like you are always new to the game - when you don't actually need any help and you just want to think for yourself. Another example situation is doing a repetitive task which you already have experience with, and yet the person continually tries to 'teach' you when you don't need help/already know how to do it. It almost makes you mad because you really don't need help. As an example which recently happened to me:  &quot;Hey, do you remember how to start the wood chipper?&quot; &quot;Yes I do&quot; &quot;Okay, well, let me show you one more time&quot;  Again, is there a term for someone who does this? What is the distinction between a professional and amateur photographer? Add notes under the table I'm using the latex package  because the  package isn't using APA style version 6 yet.  Now I'm trying to add a table with notes right underneath it, like in this table for instance:    Since the \caption{} is used as a title above the table, I have to add an extra row for the notes that goes over the whole table width. The problem is that the notes won't fit into one line so I need multi-line cell. How can I accomplish that? Or am I doing it totally wrong and there is a much easier way? I guess footnotes don't work here.  \documentclass{apa6e}  \begin{document} \shorttitle{} \begin{table} \caption{title} \begin{tabular}{cc} foo &amp; bar\\ \hline \multicolumn{2}{l}{Notes. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras lacus orci, porttitor et posuere sit amet, tempor non justo. Ut quis aliquet turpis. Ut dictum nulla eget purus elementum a lacinia libero varius. Donec malesuada nulla ut odio rhoncus convallis. Aenean faucibus sollicitudin sapien, a vestibulum ante rhoncus sit amet. In vitae mi justo. In arcu metus, porta et lacinia ut, ultricies sed eros.} \end{tabular}  \end{table} \end{document} As you can see from the image below, I have an issue with the text alignment of extra long chapter names. How can I fix it so that the text will not go further left than the start of the chapter name? That is, I don't want any text to be underneath the "Appendix A" part.  I added that red line just to show how I'd like it aligned, if possible.    Here's my MWE:  \documentclass{book} \let\cleardoublepage\clearpage  \RequirePackage{titletoc} \RequirePackage{tikz} \RequirePackage[explicit]{titlesec} \RequirePackage{DejaVuSansCondensed} \RequirePackage[normalem]{ulem} \RequirePackage[   left=2.25in,   right=0.75in,   top=1.25in,   bottom=1.25in,   marginparwidth=1.75in,   marginparsep=.25in,   asymmetric]{geometry}  \renewcommand*\familydefault{\sfdefault} % Set default font  %%% Table of Contents ---------------------------------------------------------- \setcounter{tocdepth}{1} % Show only Chapters and Sections  %%% Change font/color/layout of TOC \makeatletter \titlecontents{chapter}[-2em] {\color{cyan}\bfseries\LARGE\addvspace{3mm}} {\makebox[4.4em][r]{\@chapapp}\contentslabel{-0.25em}\hspace{1.9em}} {} {\hspace{3em}\contentspage} \g@addto@macro{\appendix}{%   \addtocontents{toc}{\protect\renewcommand*{\protect\@chapapp}{\protect\appendixname}}% } \makeatother  \titlecontents{section}[5.3em] {\color{cyan}\large\itshape\addvspace{3mm}} {\contentslabel{0em}\hspace{3.2em}} {} {\hspace{3em}\contentspage} [\addvspace{0mm}]  %%% Chapter Header ---------------------------------------------------------- \makeatletter \titleformat{\chapter}   {\normalfont\sffamily\Huge\scshape}   {}{0pt}   {\thispagestyle{empty}    % Remove page number on new chapters   %\setcounter{definition}{0}   \begin{tikzpicture}[remember picture,overlay]     \node[yshift=-3cm] at (current page.north west)       {\begin{tikzpicture}[remember picture, overlay]         \draw[fill=cyan] (0,-1) rectangle           (25cm,3cm);         \draw[fill=cyan] (0,-24) rectangle           (25cm,-25cm);         \ifttl@label% &lt;---------------------- Added condition on \ifttl@label           \node[anchor=west,xshift=.21\paperwidth,yshift=-.01\paperheight,rectangle]               {\color{white}\LARGE \MakeUppercase{\@chapapp} \Huge\thechapter};         \fi% &lt;------------------------------- end condition on \ifttl@label        \end{tikzpicture}       };    \end{tikzpicture}\endgraf   \vskip-.7cm   \color{cyan}\Huge\raggedright\leftskip-1cm    \noindent\MakeUppercase{#1}\endgraf   } \makeatother  \titlespacing*{\chapter}{0pt}{10pt}{0pt}{}  \titleformat{\section}{\color{cyan}\itshape\LARGE}{\llap{\thesection} #1}{1em}{}[\titleline{\color{cyan}\titlerule[1pt]}] \titleformat{\subsection}{\color{cyan}\normalfont\large}{\; #1}{1em}{}  \begin{document}   \tableofcontents   \chapter{Turing Machines}     \section{The Turing Machine}     \section{Variations of the Turing Machine}       %\subsection{Non-deterministic Turing Machines}     \section{The Church-Turing Thesis}   \chapter{Decidability}     \section{The Universal Turing Machine}    \appendix   \chapter{ON COMPUTABLE NUMBERS, WITH AN APPLICATION TO THE ENTSCHEIDUNGSPROBLEM} \end{document} When voting to migrate an off-topic question, why is the list of sites limited? Earlier, I voted to close  as off-topic.  The question has since been closed.  There is an , but it didn't show up in the list when I selected "off-topic".  The options were:   Meta Stack Overflow Server Fault Super User Webmasters Programmers   Questions:   Should Wordpress appear in this list? Are there any other sites that should appear in the list?   Should all non-beta sites appear in that list by default? I am trying to prove the following statement.     If a field $K$ is not algebraically closed, then any $K$-variety $V\subset\mathbb{A}^n$ can be written as the zero set of a single polynomial in $K[X_1,X_2,...,X_n].$     Suppose $V=V(f_1,f_2,...,f_n)$, and I would want to find a polynomial $g\in K[X_1,X_2,...,X_n]$ such that $V=V(g)$.  I know that if I can find a polynomial $\phi\in K[X_1,X_2,...,X_n]$ whose only zero is $(0,0,...,0)$, then it is done, since we could take $g=\phi(f_1,f_2,...,f_n)$.  For $n=1$, then I would just choose $\phi=X$, but I do not even know how to proceed to the case $n=2$. Maybe we could choose an irreducible polynomial of degree $&gt;1$.  Any help will be appreciated. "I cannot seem to find it" Using MySQL, I can do something like:  SELECT hobbies FROM peoples_hobbies WHERE person_id = 5;   My Output:  shopping fishing coding   but instead I just want 1 row, 1 col:  Expected Output:  shopping, fishing, coding   The reason is that I'm selecting multiple values from multiple tables, and after all the joins I've got a lot more rows than I'd like.  I've looked for a function on  and it doesn't look like the CONCAT or CONCAT_WS functions accept result sets.  So does anyone here know how to do this? Why isn't there a potential difference across a disconnected diode? I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere.  The reason I ask this though is that from my understanding of the depletion region and built in potential of a diode it seems like if you connected a voltmeter across the whole diode it would show the value of the built in potential.  This is explained in the image below:    At first, electrons flow from the n type to the p type because there are a higher concentration in the n type, and holes do vise versa. This is called the diffusion current. The first electrons and holes to cross the pn boundary are the ones which are closest to it; these carriers recombine when they meet each other and are then no longer a carrier. This means there is a depletion region of no carriers near the pn boundary. because electrons have left the n type material, and holes have left the p type material, there is a surplus of positive and negative charge on the n and p side of the pn boundary respectively. This causes an electric field that opposes the diffusion current, and so no more electrons or holes cross the boundary and combine. In short, only the electrons and holes near the boundary combine, because after they have done that an electric field is formed that prevents any more carriers from crossing. The current due to this electric field is called drift current, and when in equilibrium this will equal the diffusion current. Because there is an electric field at the boundary (pointing from the positive charge to the negative charge) there is an associated voltage. This is called the built in potential.  If you sample the electric field at each point along the diode from left to right, you would start with 0 in the p region because there are an equal number of protons and electrons. As you approach the depletion region you would see a small electric field pointing back towards the p region, caused by acceptor impurities which now have an extra electron (due to recombination) and therefore now have a net negative charge. This electric field would increase in strength as you get closer to the boundary, and then die away as you get further away.  This electric field means there is a voltage, as shown in graph (d). The p side is at an arbitrary potential, and the n side is at a potential higher than this because there is an electric field between them. This means there is a potential difference across the depletion region; this is known as the built-in potential.  But why when I connect a volt-meter across the whole diode will I not see this built in potential? Converting to upper and lower case in Java android - out of memory exception when creating bitmap Can I find out which tags I have created?