Importing project from tutorial source results in R cannot be resolved to a variable
"R cannot be resolved to a variable"?
LibVLC.NET in GTK# Script to change current directory (cd, pwd) I want to run a script to simply change the current working directory:  #!/bin/bash cd web/www/project   But, after I run it, the current pwd remains unchanged! How can I do that? Changing subject and verb positions in statements and questions How accurate is approximating the Earth as a sphere? What level of error do I encounter when approximating the earth as a sphere? Specifically, when dealing with the location of points and, for example, the great circle distances between them.  Are there any studies on the average and worst case error compared to an ellipsoid? I'm wondering how much accuracy I'd be sacrificing if I go with a sphere for the sake of easier calculations.  My particular scenario involves directly mapping WGS84 coordinates as if they were coordinates on a perfect sphere (with the  defined by the IUGG) without any transformation. How do I remove a file I accidentally created named $file? I was working on a shell script and I accidentally created a file with the variable as its name. Now I have $file in my ls output, and cannot remove it.  What can I do? Horizontal line of custom length like an — Is there a way to get a custom-length horizontal line that appears like a "longer em-dash", if you will? In my student book they separate these two and indicate that sparks need high voltage to occur while arcs need low voltage with normal or low pressure and electric arcs CAN come with heat and bright light. But when I search on the web many people said that arc is just a hotter version of spark. So what is the difference between them? Is there a systematic way of finding the conjugacy class and/or centralizer of an element? Is there a systematic way of finding the conjugacy class and centralizer of an element? Could the task be simplified if we are working with "special groups" such as $S_n$ or $A_n$? Are there any intuitive approaches? Thanks. How to draw tangent vectors and component vectors on a curve I am searching for a way to have a figure drawn using LaTeX. I am aware of some packages TikZ and PSTricks that could accomplish this, and have been tinkering around with them recently but do not have enough skill set at the moment to accomplish this drawing. Is there a way someone can accomplish the drawing, preferably with TikZ but could be any package your most comfortable with in a reduced amount of coding (non-advanced) to where I could understand what is happening from the code to the picture. If this is not possible, then I will have to study the package more and work with it until I understand the method (code) to create the graphic. The drawing is below.  Note: This is a rough sketch. The optimal output would have smooth quadratic curves and all quantities are vectors. Does Exchange support disposable e-mail addresses? Sometimes it is useful to have e-mail address like foo-randomnumber@example.org, where randomnumber identifies the conversation between a robot such as a mailing list server and a user. Is this possible with Microsoft Exchange? Why do Lambertian Reflectors Privilege the Observer? How should the "and/or" text of a card be interpreted? How should the "and/or" text of a card be interpreted? For example on a card like  the text reads:     Nahiri's Wrath deals damage equal to the total converted mana cost of the discarded cards to each of up to X target creatures and/or planeswalkers.   For the remainder of this question, let's fix X at 2 to keep things simple.  Should the "and/or" be interpreted such that the effect is applied to a combination of targets the player chooses. That is to say for Nahiri's Wrath the player could perform one of the following options:   Nahiri's Wrath deals damage to each of two target creatures. Nahiri's Wrath deals damage to each of two target planeswalkers. Nahiri's Wrath deals damage to each of one target creature and one target planeswalker.   Or should the card's effect be expanded and applied to both sides of the "and/or". With this interpretation the player would have to the following two options when playing Nahiri's Wrath:   Nahiri's Wrath deals damage to each of X target creatures and Nahiri's Wrath deals damage to each of X target planeswalkers Nahiri's Wrath deals damage to each of X target creatures or Nahiri's Wrath deals damage to each of X target planeswalkers   The confusion stems from  (which was formerly formerly worded using the same phrasing) where some commenters have said things like:     So this lets you do a total of 12 damage? 3 each to 2 target creatures AND 3 each to 2 target players, one of which could be a planeswalker? That's how the "and/or" works, right? You can choose. Otherwise it would just be "or"... I can use my mobile broadband to access Internet with Firefox but when I want to install any package from terminal or make 'apt-get update' command I got the following error:  got 'NODATA' (does the network require authentication?)   apt-get update output:  Get:1 extras.ubuntu.com trusty InRelease [213 B] 98% [1 InRelease gpgv 213 B] [Connecting to archive.ubuntu.com] Splitting up /var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_trusty_InRelease into data Ign extras.ubuntu.com trusty InRelease E: GPG error: extras.ubuntu.com trusty InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)    output of `cat /var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_trusty_InRelease  &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"&gt; &lt;html&gt; &lt;head&gt; &lt;title&gt;404&lt;/title&gt; &lt;meta http-equiv="Cache-Control" content="no-cache"/&gt; &lt;/head&gt; &lt;body&gt; &lt;p&gt; Not Found &lt;/p&gt; &lt;/body&gt; &lt;/html&gt;   output of wget:  wget -O - http://extras.ubuntu.com/ubuntu/dists/trusty/InRelease  --2014-06-01 09:23:35--  http://extras.ubuntu.com/ubuntu/dists/trusty/InRelease Resolving extras.ubuntu.com (extras.ubuntu.com)... 91.189.92.152 Connecting to extras.ubuntu.com (extras.ubuntu.com)|91.189.92.152|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 213 [text/html] Saving to: ‘STDOUT’   0% [                                       ] 0           --.-K/s              &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"&gt; &lt;html&gt; &lt;head&gt; &lt;title&gt;404&lt;/title&gt; &lt;meta http-equiv="Cache-Control" content="no-cache"/&gt; &lt;/head&gt; &lt;body&gt; &lt;p&gt; Not Found  &lt;/p&gt; &lt;/body&gt; &lt;/html&gt; Is there a quick way to reset a .blend files windows and settings to default Whenever I download a .blend from someone all of the windows and settings are the way they have left them as it is saved in the file. It takes way to long to rearrange every window and toolbar to the way it is by default. Is there any tool or shortcut that can reset the UI to blenders default and just leave the actual contents of the file? The only way I could do this is by creating a new file and using link/append but this is not the best option. Underlined math in a Beamer presentation: felt-tip marker underlining Is the following conjecture true?     Given an $n&gt;1$ and a $k$ such that $0&lt;k&lt;n$ then $\gcd\left(\binom{n}{k}, n\right)&gt;1$   This was a question asked in my old Number Theory course that I recently remembered. It was posed after we learned that $p\mid\binom{p}{k}$ for $0&lt;k&lt;p$. We never resolved it either way. I expect it to be true and have an elegant answer, but I haven't been able to prove it. My number is associated with iMessage on other phone, how to remove it? Good day everyone. For only 1 hour (!) I used my relatives iPhone with my sim card and that's it, he keeps receiving all of my iMessages. I tried checking in iTunes all devices associated with my account and his device is not listed. I tried to log in and log out to/from iMessage on his phone with his apple ID, still won't help. How can I stop this nightmare!? When I go to iMessage settings>Send &amp; Receive on his device, there is only my phone number listed, how do I remove it without smashing phone to the wall?! Thanks and have a great day  EDIT. After talking to apple support for some time, they removed my phone number from my friend's iMessage. So I guess if you are facing same problem you have to contact support. I have two shapefiles, Point and Polyline. I'm trying to populate my polyline layer with the point data ID (systemID) where the lines start to where they end; eg. create two columns (from and to). The lines already have flow direction assigned to them. I am using ArcHydro tools but Arcpy is also fine.  In ArcHydro I have tried using Attribute Tools > Generate From/To Nodes for lines but it creates values for To and From that are not from my point data. My other alternative was using Feature to Vertices and joining the result to my point data table to get the systemID. But then I would have to update the polyline layer as well. I am sure there is a easier way of doing it.  Note: not all the lines have points at the vertices, blank values are fine for them. Let $X,Y,Z$ be subspaces of $V$ so that $X$ is a subspace of $Y$. Prove that $Y\cap (X+Z)=X+(Y\cap Z)$ Let $X,Y,Z$ be subspaces of $V$ so that $X$ is a subspace of $Y$. Prove that $Y\cap (X+Z)=X+(Y\cap Z)$  I know that I need to prove that $Y\cap (X+Z)\subseteq X+(Y\cap Z)$ and $X+(Y\cap Z)\subseteq Y\cap (X+Z)$ but I´m having a hard time.  Can you lend me a hand please? I would really appreciate it How to backup settings and list of installed packages If I want to make a backup of everything I have done since the fresh install of Ubuntu, what are the possible options? What all should I backup? I want to get all the settings that I changed, all the packages I installed, etc.