Java update not working?
How to properly install Java in OS X
Regression with only categorical variables Is it possible to conduct a regression if all dependent and independent variables are categorical variables? I’m using tikz-cd for diagrams, and have a medium-sized diagram that I want to re-use several times.  However, when I try using a definition like:  \newcommand{\myarrow}{$\begin{tikzcd} A \ar{r} &amp; B \end{tikzcd}$   I get an error:  ERROR: Package pgfbasematrix Error: Single ampersand used with wrong catcode.   Is it possible to put a tikz-cd diagram into a defined command somehow? I did the following proof and I was wondering if its valid. It feels wrong because I didn't actually test the case when purportedly $n$ is not prime, but please feel free to correct me.  Assume there exists $n$ such that $\phi(n) = 14$. Assume $n$ is prime. Then $\phi(n) = n-1$. Then here, n-1 = 14, so n = 15.  We know since Euler's totient function is multiplicative that $\phi(xy)$ = $\phi(x)\phi(y)$, so $\phi(15) = \phi(3)\phi(5)$, but alas $\phi(3)\phi(5) = 2\cdot4 = 8 \ne 14$. If $n$ is not prime a similar argument follows since we know then that $n$ must be composed of prime numbers by the prime factorization theorem. i would like to know how to prove that if $a^2+b^2=c^2$ then   a) $3|a$ or $3|b$  b) $5|a$ or $5|b$ or $5|c$  c) $4|a$ or $4|b$   Also that $a^2+b^2+c^2+1$ can't be divisible by 8  Thank you very much! Why does copying the same amount of data take longer if spread across many separate files? I noticed that copying 24Mb worth of data from one folder to another took about 30 seconds because (I'm assuming this is the reason) it was over 1,000 separate files. Copying 24Mb shouldn't take so long. Why does the number of files make a different?  I'm running Windows 7 on a MacBook (4GB ram, Intel(R) Core(TM)2 Duo CPU P7450 @ 2.13GHz, 32-bit Operating System)  EDIT: NTFS is the file system used on the drive Cryptoclass Throws Error. Invalid private key. Must be 16 bytes. Sending 16 characters long key key__c :- abcdefghijklmnop  public static String decrypt(String data) {     EncryptionSettings__c settings = EncryptionSettings__c.getOrgDefaults();     if (settings.key__c == null) {         throw new FacebookException('Cannot decrypt without a key!');     }     Blob key = EncodingUtil.base64Decode(settings.key__c);     return Crypto.decryptWithManagedIV('AES128', key, EncodingUtil.base64Decode(data)).toString(); }  public static String encrypt(String data) {         EncryptionSettings__c settings = EncryptionSettings__c.getOrgDefaults();     Blob key = null;     if (settings.key__c == null) {         checkUserCanCustomizeApplication();         key = Crypto.generateAesKey(128);         settings.key__c = EncodingUtil.base64Encode(key);         insert settings;     } else {         key = EncodingUtil.base64Decode(settings.key__c);     }     return EncodingUtil.base64Encode(Crypto.encryptWithManagedIV('AES128', key, Blob.valueOf(data))); } Downloading files instead of opening directly I have kept files in site assets and created hyperlinks to the files (which may be PDF or word ). When i click on the link it opens up in the browser. How do i force it to download ? Prime dividing the binomial coefficients It is quite easy to show that for every prime $p$ and $0&lt;i&lt;p$ we have that $p$ divides the binomial coefficient $\large p\choose i$; one simply notes that in $\large \frac{p!}{i!(p-i)!}$ the numerator is divisible by $p$ whereas the denominator is not (since it is a product of numbers smaller than $p$ and $p$ is prime).  My problem is with generalizing this argument for $q=p^n$. I'm looking for the most elegant and simple way to prove that $p$ still divides $\large q\choose i$. Backup with duplicity on Google Cloud Storage I have already set a backup routine that backups all my files to Amazon S3 using duplicity. I would like to create a similar backup routine with Google Cloud Storage. Is it possible to get duplicity to work with GCS? I'm creating a function where I need to pass an object so that it can be modified by the function. What is the difference between:  public void myFunction(ref MyClass someClass)   and  public void myFunction(out MyClass someClass)   Which should I use and why? What can you say about the range space and null space Let $V$ be a vector space over a field $F$ and $T$ a linear operator on $V$. If $T^2$$=$ $0$, what can you say about the relation of the range of $T$ to the null space of $T$? How to find Windows 7 File Transfer History? Why was Hagrid's wand snapped in two when he was expelled from Hogwarts? Why was he banned from performing magic? Yes, he was expelled from Hogwarts after being framed by Tom Riddle as being responsible for Moaning Myrtle's death via Aragog the Acromantula. But why did he receive this punishment?  ‘What’ve you been feeding [the pumpkins]?’ said Harry. Hagrid looked over his shoulder to check that they were alone. ‘Well, I’ve bin givin’ them – you know – a bit o’ help.’ Harry noticed Hagrid’s flowery pink umbrella leaning against the back wall of the cabin. Harry had had reason to believe before now that this umbrella was not all it looked; in fact, he had the strong impression that Hagrid’s old school wand was concealed inside it. Hagrid wasn’t supposed to use magic. He had been expelled from Hogwarts in his third year[...] Chamber of Secrets - page 90 - Bloomsbury - chapter 7, Mudbloods and Murmurs  Why would Hagrid's wand be snapped in two and he not be allowed to do magic when:  Attendance and completion of an education at Hogwarts was not compulsory by wizarding law¹; homeschooled children were allowed to do magic for their lessons, and then do magic fully when they turned 17. The Weasley twins dropped out of Hogwarts after practically destroying parts of the castle with fireworks (and conjuring an awesome swamp on the fifth floor), yet were allowed to do magic despite not completing Hogwarts or any kind of homeschooling curriculum (that we know of). No Death Eater character that we know of was banned from using magic, despite their crimes and devotion to Voldemort. I don't recall any Death Eater wands being snapped and the owner banned from performing magic after being convicted of Death Eater crimes (please do correct me if I'm wrong). For example, Bellatrix Lestrange's wand was not snapped in Goblet of Fire when she received a life sentence in Azkaban and, as we know, her wand played a fairly significant part in Deathly Hallows.  ¹I realize in Deathly Hallows Voldemort made attendance at Hogwarts compulsory; however, by that time, Hagrid had been cleared of the charges of being responsible for Myrtle's death and was allowed to use magic again. UK Visa Status check I have a US Green Card and applied for UK visa (Travel Visa) last month but haven't heard anything back from the New York Office. I am travelling on the 19th and am really concerned. They don't have any phone no. or email other than NEYOZVisaInfo@fco.gov.uk (it says incoming mail cannot be monitored).  Please assist. Possible to get type of an aliased type in c#? Type.GetType("System.String")   Is there a lookup for the aliases available somewhere?  Type.GetType("string")   returns null. Badge Name is Blue? Now some random badges on the Profile page for the mobile web is now blue! This is seemingly weird as the default and now permanent color for Badge name text is white. Here's the problem here:     Ahhhh! Now it has invaded the desktop/computer version too! Now seemingly, every version has badges with blue text. Android app has the same issues too! Can the badge color be fixed from blue to white on the mobile version please? How can I charge my iPhone without waking up my MacBook Pro? How can I make a div not larger than its contents? Let $x, y$ and $z$ be real numbers such that $x^2+ y^2+ z^2= 1$. Find the   maximum and minimum values of $2x + 3y + z$ .       How can I able to solve the problem? Thanks for your help. Feed can show entries for deleted posts, which viewing them fails Just noticed this:  Someone @replied to me in a question which appropriately showed up in my feed.  I go to click on that notice in the feed, and it presents me with "Loading the question failed."  I'd show a picture, but I don't think that it's entirely relevant - I believe it's reproducible if an answer is posted, someone makes a reply, the answer is removed, then that someone else goes back in the feed to try and revisit the post.  Alternatively, why not synchronize the interface between what a 10K user sees on the site, and what they see in the app?  As a 10K user, I would expect to see deleted questions and answers.