Update computer to latest version but the version we have is 8.10 and it is not upgrading to version 13.10. I message I see is "server error". I dont know how to update in another way.
Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc
How can I mirror one of the screens in a 3-monitor setup? On Windows 7, is there a command prompt line that can start cmd as an administrator? On Linux, we can use  sudo bash   to run a shell as the superuser.  On Windows 7, we can use     Start menu -> (in search box, type) cmd -> Right click on search result and choose Run as Administrator   to run a command prompt as an administrator. Is there also a command prompt line that is like Linux's sudo or su so as to start a shell as an administrator? Why might right aligned field labels be better? For the longest time, I've used left-aligned labels in my forms, like this:    I did this because I thought having the labels left aligned made it easier for readers to scan the list of labels.  However, I found my axiom challenged recently while watching  from , in which Billy asserts that right-aligned labels are simply better, like this:    I've done a bunch of research and found a lot of discussion, including , which compares and contrasts the approaches, but nothing definitive.  In particular, I haven't been able to find anything to indicate why Billy Hollis changed his opinion from left- to right- alignment for labels (apparently he switched around 2007).   I figure Billy's too smart to have made the change without evidence - so I'm interested in seeing that evidence for myself. When should "into" be used rather than "in to," and vice versa? "Into" (one word) and "in to" (two words) are frequently confused.  In what situations should the former be used?  The latter? How can I recreate geometry using a photograph? Prove that if $d$ divides $n$, then $2^d -1$ divides $2^n -1$ Prove that if $d$ divides $n$, then $2^d  -1$ divides $2^n  -1$.  Use the identity $x^k  -1 = (x-1)*(x^{k-1}  +  x^{k-2}    + \cdots + x +1)$ When choosing cards for a deck, one of the most important things to consider is the number of land you put in. The biggest issue is mana curve, of course. What shortcuts are best for determining the proper amount of land with a given mana curve? Apps retaining data after being deleted I am having trouble loading csv files into layers using QgsVectorLayer().  I know this looks like a repeat, but I have carefully read     and    but still cannot get it work.  An example of my data file, test.csv:  Index,y,x 0,37.7646618,-122.4960858 1,37.777494,-122.416311 2,37.717707,-122.3997056 3,37.732284,-122.498118 4,37.749998,-122.392333   My code:  import os import urllib  import pathlib from qgis.core import QgsVectorLayer  local_path = 'C:\dev\FCMS_conflation\data\TMC_nodes.csv' node_layer = 'test'  abspath = os.path.abspath(local_path) params = {'delimiter': ',',           'decimalPoint': '.',           'xField': longitude,           'yField': latitude}  uri = "%s?%s" %(pathlib.Path(abspath).as_uri(), urllib.unquote(urllib.urlencode(params)))  layer = QgsVectorLayer(uri, node_layer, "delimitedtext")   The formatted URI looks like:  [] uri &gt;&gt;&gt; 'file:///C:/dev/FCMS_conflation/data/TMC_nodes.csv?decimalPoint=.&amp;delimiter=,&amp;xField=longitude&amp;yField=latitude'   I have tried many variations of the parameters, including the crs and type. But no matter what I try, I cannot create a valid layer.  [] layer.isValid() &gt;&gt;&gt; False   I have verified that I can add the file using the QGIS gui. I even tried using the uri provided by layer.metadata from within the Python plugin.   I am using QGIS 2.10.1 on Windows 7 64-bit machine. How do users get started on new Stack Exchange sites? How do users on the new Stack Exchange sites get started? Each user starts with 1 rep, and can't upvote until they have 15 rep.  It struck me that this creates a bit of a deadlock. If a new user asks a question and a new user answers, neither can upvote the other.  Are we relying solely on existing SE users to join these exchange sites (with their bonus 100 rep) so that they can get started? Can Hooke's law be derived? Can we derive  from the theory of elasticity? I know it is not a fundamental law and therefore can be derived from more basic considerations. I've got two tables:  TableA ------ ID, Name  TableB ------ ID, SomeColumn, TableA_ID (FK for TableA)   The relationship is one row of TableA - many of TableB.  Now, I want to see a result like this:  ID     Name      SomeColumn  1.     ABC       X, Y, Z (these are three different rows) 2.     MNO       R, S   This won't work (multiple results in a subquery):  SELECT ID,        Name,         (SELECT SomeColumn FROM TableB WHERE F_ID=TableA.ID) FROM TableA   This is a trivial problem if I do the processing on the client side. But this will mean I will have to run X queries on every page, where X is the number of results of TableA.   Note that I can't simply do a GROUP BY or something similar, as it will return multiple results for rows of TableA.   I'm not sure if a UDF, utilizing COALESCE or something similar might work? Is there a simple command for the available height in a beamer slide? How to detect scene strips in the VSE on frame changes? I need to detect scene strips in the VSE on the current frame, meaning on what strip is the play head at this moment? However I can't seem to find the right type(?) to attach the ".strip_elem_from_frame" function to, in order to get the info/name/type on the strip. Here's a test script which must run in a screen with a sequencer with scene and movie strips in it:  import bpy  #update at frame change def currentStrip(*pArgs):     print("Current Strip: "+str(bpy.context.sequences[0].strip_elem_from_frame(bpy.context.scene.frame_current))) #Doesn't detect any strips at all.  #add frame change handle def attachAsHandler():     for f in bpy.app.handlers.frame_change_pre:         bpy.app.handlers.frame_change_pre.remove(f)     bpy.app.handlers.frame_change_pre.append(currentStrip)  currentStrip() attachAsHandler() Protect Google Spreadsheet formatting while allowing changes to data I would like to protect the formatting of a cell (or a range of cells) in a Google Spreadsheet, but still allow changing the data in that (or those) cell(s).  For example, I want to add a validation rule on a cell that says the cell has to contain a number between 1 and 10, and I would like others to be able to change the value in that cell, but not the validation rule itself.  How do I do that?  So far I was only able to completely protect the cell (content + formatting) or not at all (the user can change the content as well as the formatting).  To me this seems to be an important functionality when adding access rights to spreadsheets. Is it possible that it is completely missing from Google Spreadsheets? Can't get unicode symbols in math mode I am trying for about a week to launch unicode-math package with XeLaTeX and got nothing. PDF is created well but all Cyrillic symbols in math mode are skipped. I tried using different math fonts - no progress at all. In log file, I found low-level error:  Missing character: There is no [cyrillic letter from input] in font cmmi12!   But all fonts used in document are Unicode ones.  Here is a file I want to be processed well (of course it is UTF-8).  \documentclass[12pt]{book} \usepackage{polyglossia} \setdefaultlanguage[spelling=modern]{russian} \setotherlanguage{english} \defaultfontfeatures{Ligatures={TeX}} \setmainfont{CMU Serif} \setsansfont{CMU Sans Serif} \setmonofont{CMU Typewriter Text}    \usepackage{amsmath, amssymb} \usepackage[russian]{hyperref}  \usepackage{unicode-math} \setmathfont{Latin Modern Math}  \frenchspacing  \begin{document} Просто буквы % Plain letters $$Память: M_{доп}(n) = \Theta(N)$$ % Memory: M_add(n) = \Theta(n) \end{document}   Looking for your help. An example to show that convergence of Cesaro sum to $0$ does not imply the original sequence converges to $0$. I'd like construct a non-negative sequence $\{a_{k}\}_{k=0}^{\infty}$ with $a_{0}=0$ such that the Cesaro sum $\frac{1}{n}\sum_{k=0}^{n-1}a_{k}\longrightarrow 0$ but $a_{n}$ does not converge to $0$.   I have a really bad attempt:  Define $a_{0}=a_{1}=0$, and $a_{k}:=\log(\log(k))$ for $k\geq 2$, then $a_{k}\longrightarrow\infty$. But $$\dfrac{1}{n}\sum_{k=0}^{n-1}a_{k}=\dfrac{\log\Big(\prod_{k=2}^{n-1}\log(k)\Big)}{n}$$ and Wolframalpha told me that this series converges to $0$ as $n\longrightarrow\infty$.  However, I have no idea about how to show this convergence to $0$. Also, I wish to have a sequence as simple as possible, since at some stage I need too how $f(k):=a_{k}$ is positive semi-definite.   Is there any simpler example?   Thank you! How to count number of words from String using shell Proving Pascal's identity So I came across Pascal's identity: Prove that for any fixed $r\geq 1$, and all $n\geq r$, $$ \binom{n+1}{r}=\binom{n}{r}+\binom{n}{r-1}. $$  I know you can use basic algebra or even an inductive proof to prove this identity, but that seems really cumbersome. I was wondering if anyone had a "cleaner" or more elegant way of proving it. For example, I think the following would be a decent combinatorial proof.   Proof: Let $S$ be a set with $n+1$ elements, and consider some fixed $x\in S$. There are $\binom{n+1}{r}\;\; r$-subsets of $S$--count them according to whether or not they contain $x$: there are $\binom{n}{r}$ not containing $x$, (each formed by choosing $r$ of the remaining $n$ elements in $S\setminus\{x\}$), and there are $\binom{n}{r-1}\;\; r$-sets containing $x$, (each formed by selecting an additional $r-1$ elements in $S\setminus\{x\}$).   Is that right? Are there any other efficient ways of doing it? I am considering to create a wiki/blog for most of my study notes that I have made or taken digitally.  Also, for the handwritten and rough ones I am thinking about storing them in my GitHub repository.  Is this a good idea? How do professionals in academia and PhD students organise their notes?  Also, should I keep my notes publicly available?  Edit: The main purpose of keeping my notes public is to have them readily available and searchable of myself and my immediate peers in college. If that benefits someone else, I will be more than glad to have helped.   Update regarding having a blog/wiki: I was thinking about having stuff regarding my take on a certain topic or similar rather than just straightaway putting mugged up lecture notes. (as I mentioned in a comment)  So basically, as I go along a certain topic whatever interesting I find, I post  it. Also I will put in links to papers, books and other interesting literature on the topic that might be helpful while studying the topic. This seems easier to deal with and also serves as a way to track my current interests and/or workflow.