I keep getting this failed message and I don't know how to fix it.  These are the details in the error:  W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/source/Sources  404  Not Found [IP: 2001:67c:1562::15 80] W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/main/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1562::15 80] W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1562::15 80] W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1562::15 80] W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/multiverse/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1562::15 80] W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-i386/Packages  404  Not Found [IP: 2001:67c:1562::15 80] W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/binary-i386/Packages  404  Not Found [IP: 2001:67c:1562::15 80] W:Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/multiverse/binary-i386/Packages  404  Not Found [IP: 2001:67c:1562::15 80] E:Some index files failed to download. They have been ignored, or old ones used instead.
PPA seems to be constantly offline. Whenever I use sudo apt-get update, this error is shown:  W: Failed to fetch http://ppa.launchpad.net/ 404  Not Found   How do I fix these errors?
Get file size before uploading The generating function for the Fibonacci numbers I want to merge two shape files in which one is of point geometry type and other is polygon type in order to get a single layer containing both points and polygon in a single map. Let a be a positive number. Then $\lim_{n \to \infty}[\frac{1}{a+n}+\frac{1}{2a+n}+\cdots +\frac{1}{na+n}]$ Auto-inserting Stack Overflow affiliate into all Amazon links We have officially discontinued the Amazon book affiliate remnant ads, since despite our best efforts they don't perform well for our audience and cannot be made to perform well.  We've often wondered,   I'm thinking this isn't a problem; it has gotten lots of support historically. So we're going to go ahead and do it, so the company Amazon account is still getting some use, and we benefit a little.   To be clear: from this point on, all Amazon links posted on all sites will automatically be rewritten to add our affiliate link. We have a clever affiliate redirect that geolocates the IP address and redirects to the appropriate regional Amazon store (amazon.uk, amazon.ca, et cetera).  If you have any feedback on this, or suggestions, as they say &hellip; speak now or forever hold your peace! What's the difference between the atomic and nonatomic attributes? What do atomic and nonatomic mean in property declarations?  @property(nonatomic, retain) UITextField *userName; @property(atomic, retain) UITextField *userName; @property(retain) UITextField *userName;   What is the operational difference between these three? What program can I use to decompile a class file? Will I actually get Java code, or is it just JVM assembly code?  On Java performance questions on this site I often see responses from people who have "decompiled" the Java class file to see how the compiler optimizes certain things. Unable to stylize raster data as pseudocolor render type on MAC OSX In a raster layer's Style Properties, I can choose pseudocolor render type, and choose a color ramp and classify the raster.      However, when I click the 'Apply' button, or click 'OK', the visualization of the raster never changes.  I was able to output a 'colorized' version of the same raster using GRASS plugin.  I also reinstalled QGIS 2.8, and was able to adjust and see a raster stylings using the steps I outlined above.  So, can anyone confirm this as an issue, or confirm that there's a mistake somewhere in my process?  I should note that I'm on a Mac, 10.10.4, and I'm using the QGIS provided by , 2.10.1-1 .  Update 1: Here's a screenshot of the rest of my settings.      I have Grayscale set to off in the Style setting.  Also, I don't believe grayscale/color-blind Preview is available on the Mac version of QGIS.  They're does't appear to be the option where it , in the Menu Bar under View / Preview / Photocopy (grayscale) etc.  Either way-- I added a shapefile to show color.  Update 2: I've experimented with setting color interpolation to discrete, linear, and exact, but still am not able stylize using Singleband pseudocolor.  I've also confirmed that the 'Render' box on the the main map view is checked.  Also, I am able to adjust Color Rendering settings, like Hue, Blending Mode, etc., and see the results when clicking 'Apply' or 'OK'.  Update 3: As other Mac users are confirming this, I think it may be a bug. I've created a bug report at the official . How to access the shared folder between two computers running ubuntu I have to computers running Ubuntu and I want to share files between those computer. these computers are already connected through a cross cable and sharing internet connection using firestarter. Both computers have samba installed.   In Desktop computer I have a shared folder How do I access it on the other one. Questions can be closed or marked as duplicates.  What does it mean for a question to be &quot;closed&quot;? What does it mean for a question to be marked as a &quot;duplicate&quot;? Who can close a question? What are the reasons for closing a question ? Is closure the end of the road for a question? When are closed questions eligible for deletion?   Related        For more information, see &quot;&quot; in the . Scientists have found mammoth blood, and are planning to   How does one go from having its blood to a full blown living mammoth? Is it possible?    Why does it matter if the blood is frozen or not? Suppose one found dinosaur blood, could one clone a dinsosaur (as in say 'Jurassic Park')? I have a scenario where I have multiple threads adding to a queue and multiple threads reading from the same queue. If the queue reaches a specific size all threads that are filling the queue will be blocked on add until an item is removed from the queue.  The solution below is what I am using right now and my question is: How can this be improved?  Is there an object that already enables this behavior in the BCL that I should be using?  internal class BlockingCollection&lt;T&gt; : CollectionBase, IEnumerable {     //todo: might be worth changing this into a proper QUEUE      private AutoResetEvent _FullEvent = new AutoResetEvent(false);      internal T this[int i]     {         get { return (T) List[i]; }     }      private int _MaxSize;     internal int MaxSize     {         get { return _MaxSize; }         set         {             _MaxSize = value;             checkSize();         }     }      internal BlockingCollection(int maxSize)     {         MaxSize = maxSize;     }      internal void Add(T item)     {         Trace.WriteLine(string.Format("BlockingCollection add waiting: {0}", Thread.CurrentThread.ManagedThreadId));          _FullEvent.WaitOne();          List.Add(item);          Trace.WriteLine(string.Format("BlockingCollection item added: {0}", Thread.CurrentThread.ManagedThreadId));          checkSize();     }      internal void Remove(T item)     {         lock (List)         {             List.Remove(item);         }          Trace.WriteLine(string.Format("BlockingCollection item removed: {0}", Thread.CurrentThread.ManagedThreadId));     }      protected override void OnRemoveComplete(int index, object value)     {         checkSize();         base.OnRemoveComplete(index, value);     }      internal new IEnumerator GetEnumerator()     {         return List.GetEnumerator();     }      private void checkSize()     {         if (Count &lt; MaxSize)         {             Trace.WriteLine(string.Format("BlockingCollection FullEvent set: {0}", Thread.CurrentThread.ManagedThreadId));             _FullEvent.Set();         }         else         {             Trace.WriteLine(string.Format("BlockingCollection FullEvent reset: {0}", Thread.CurrentThread.ManagedThreadId));             _FullEvent.Reset();         }     } } Introductory biology text for an outsider I'm a maths major and I have an interest in learning biology. I know very, very little; I know how babies are made and that's about it. Could anyone recommend a stimulating text to read for its own sake and also to use to learn biology? I'm trying to set up file transfer via FileZilla and it doesn't seem to matter what details I put in, I always get the following error:     Status: Connection attempt failed with "ECONNREFUSED - Connection   refused by server". Error: Could not connect to server   My Dad has tried on his computer (with FileZilla on Windows) and it connects and everything is fine.. When I try on mine with all the same details that he put in, it comes up with that error.  I read that a firewall might be blocking it so I double checked and my firewall through system preferences and it is off.  Anybody know why this might be???  Additional info:  Macbook Pro running OS X El Capitan version 10.11.6  FileZilla version 3.23.0.2 Difference between "@id/" and "@+id/" in Android How to determine callee function name in a script To make it short, doing something like:  -bash$ function tt {  echo $0; }  -bash$ tt   $0 will return -bash, but how to get the function name called, i.e. tt in this example instead? Looking to draw this block diagram in Tikz I'm looking to create something like this in Tikz environment. Any tips? help? Today 4/30/20 my seemingly worthless USO call option increased in value.   Specifically: USO1 $2.5 Call 5/8  On 4/29 it was valued at $.04 and stayed there.   4/30 I checked after hours and now it’s up to $.08? Which was wasn’t even the highest it went to today.  So who is buying this contract?  Who is allowed to buy this contract? Bc I’m only able to sell and from what I understood, nobody is able to buy it.   I have screenshots and will post if requested. Thank you Let $A$ be a diagonalizable matrix and $\lambda$ be an eigenvalue of A. Prove that rank($\lambda I - A$) = rank(($\lambda I - A)^2$). We can solve the equation $x^x=c$ using the Lambert $W$ function, but how do we solve $x^{x^x}=c$ ,