KDB looping over inputs for a dyadic function
KDB: apply dyadic function across two lists
Word for phrases that are examples of what they describe Root drive is running out of disk space. How can I free up space? I'm using Ubuntu 11.04 and I want to free up some space in my root directory, which is overloaded. I especially want to change the path used for installing applications (they are getting installed directly to the root drive).  Another consideration is that I'm working on a MySQL database server. The server is installed in the root directory itself, so I don't want to  risk losing any data.  Please give me some tips to help sort out this problem. What will happen if a plane trys to take off whilst on a treadmill? When did the red shirt careers change to yellow shirts in Star Trek and why? How to prove $a^3 + b^3 +c^3 - 3abc =1 $, If a,b,c are infinite series as given in the description box below? How do I prove that $$ a^3+b^3+c^3−3abc = 1 $$ if   $ a = 1+\frac{x^3}{3!}+\frac{x^6}{6!}......$ , $b=x+\frac{x^4}{4!}+\frac{x^7}{7!}....$ , $c=\frac{x^2}{2!}+\frac{x^5}{5!}+\frac{x^8}{8!}......$ ?  I have tried the following :-  I discovered that $a+b+c=e^x$ and that $a=\frac{d(b)}{dx}$, $b=\frac{d(c)}{dx}$, $c=\frac{d(a)}{dx}$ . But I am unable to proceed further with these information. Like the subject: short sci-fi story about Earth blockaded by other human colonies.  The best humans have colonized some stellar systems. But they begin to treat humans of earth like inferiors. A war began, colonies won the war and blockaded the earth, but despite this the earth won. Who is the author? Prove the definitions of $e$ to be equivalent How to prove that the following definitions of $e^x$ are equivalent, with as simple tools as possible and without any knowledge of $e$ or logarithms ?  $$\sum_{n=0}^{\infty} \frac{x^n}{n!}=\lim_{n\to\infty}\left(1+\frac{x}{n}\right)^n$$  Also preferably, prove that this is $a^x$ for some real number $a&gt;0$. Double Range for Storm Sphere with Spell Sniper Spell Sniper says:     When you cast a spell that requires you to make an attack roll, the    spell’s range is doubled.   Can I apply that to the part of Storm Sphere that says:     Until the spell ends, you can use a bonus action on each of your turns   to cause a bolt of lightning to leap from the center of the sphere   toward one creature you choose within 60 feet of the center. Make a   ranged spell attack. You have advantage on the attack roll if the   target is in the sphere. On a hit, the target takes 4d6 lightning   damage.   The spell itself does not require the caster to make an attack roll. But there is the option to make a spell attack. I'm not sure if the Spell Sniper feat could be applied here.  Would the lightning attacks of the Storm Sphere benefit from the Spell Sniper feat? DOM event precedence What order of precedence are events handled in JavaScript?  Here are the events in alphabetical order...   onabort - Loading of an image is interrupted onblur - An element loses focus onchange - The user changes the content of a field onclick - Mouse clicks an object ondblclick - Mouse double-clicks an object onerror - An error occurs when loading a document or an image onfocus - An element gets focus onkeydown - A keyboard key is pressed onkeypress - A keyboard key is pressed or held down onkeyup - A keyboard key is  released onload - A page or an image is  finished loading onmousedown - A mouse button is  pressed onmousemove - The mouse is moved onmouseout - The mouse is moved off  an element onmouseover - The mouse is moved  over an element onmouseup - A mouse button is  released onreset - The reset button is  clicked onresize - A window or frame is  resized onselect - Text is selected onsubmit - The submit button is  clicked onunload - The user exits the page   What order are they handled out of the event queue?  The precedence is not first-in-first-out (FIFO) or so I believe. How to create an Event Notification that runs a Job/procedure when mirroring state changes I've had  on the web since 1999, and I'd like to add a page on why complex numbers are (or should be) considered to be numbers.  I'm frequently asked that question.  This is not a question about the existence or usefulness of complex numbers as they do exist as mathematical entities and they are very useful.  It is a question about what makes them numbers.  It could be broadened to ask what constitutes numbers, but I'm specifically interested in complex numbers.  Perhaps it's just historical and sociological, but I'm hoping for an answer that there's something intrinsic about complex numbers that makes them fit into the category of number. Good color palette, usable for the color blind. I'm designing a chart right now, that will slowly have more items added to it. I'd like to create an list/order of colors for the items, that will be most usable for the color blind to differentiate between each item. Any ideas how/where to start? Using Replace Geometry to replace selected feature with circle in ArcGIS Desktop? I have a polygon shapefile and I want replace every irregular polygon with a circle.  I think I can do it with the Replace Geometry tool. But once the Replace Geometry tool is selected, draw a polygon mode is immediately entered. If I select the circle tool in the Draw tool window, the Replace Geometry tool becomes inactive.  Is there any way to use the Replace Geometry tool to draw a circle polygon? Impulsioned jumping There's one thing that has been puzzling me, and that is how to implement a 'faux-impulsed' jump in a platformer. If you don't know what I'm talking about, then think of the jumps of Mario, Kirby, and Quote from Cave Story. What do they have in common? Well, the height of your jump is determined by how long you keep the jump button pressed.  Knowing that these character's 'impulses' are built not before their jump, as in actual physics, but rather while in mid-air - that is, you can very well lift your finger midway of the max height and it will stop, even if with desacceleration between it and the full stop; which is why you can simply tap for a hop and hold it for a long jump -, I am mesmerized by how they keep their trajetories as arcs.  My current implementation works as following:    While the jump button is pressed, gravity is turned off and the avatar's Y coordenate is decremented by the constant value of the gravity. For example, if things fall at Z units per tick, it will rise Z units per tick.  Once the button is released or the limit is reached, the avatar desaccelerates in an amount that would make it cover X units until its speed reaches 0; once it does, it accelerates up until its speed matches gravity - sticking to the example, I could say it accelerates from 0 to Z units/tick while still covering X units.  This implementation, however, makes jumps too diagonal, and unless the avatar's speed is faster than the gravity, which would make it way too fast in my current project (it moves at about 4 pixels per tick and gravity is 10 pixels per tick, at a framerate of 40FPS), it also makes it more vertical than horizontal. Those familiar with platformers would notice that the character's arc'd jump almost always allows them to jump further even if they aren't as fast as the game's gravity, and when it doesn't, if not played right, would prove itself to be very counter-intuitive. I know this because I could attest that my implementation is very annoying.    Has anyone ever attempted at similar mechanics, and maybe even succeeded? I'd like to know what's behind this kind of platformer jumping. If you haven't ever had any experience with this beforehand and want to give it a go, then please, don't try to correct or enhance my explained implementation, unless I was on the right way - try to make up your solution from scratch. I don't care if you use gravity, physics or whatnot, as long as it shows how these pseudo-impulses work, it does the job.  Also, I'd like its presentation to avoid a language-specific coding; like, sharing us a C++ example, or Delphi... As much as I'm using the XNA framework for my project and wouldn't mind C# stuff, I don't have much patience to read other's code, and I'm certain game developers of other languages would be interested in what we achieve here, so don't mind sticking to pseudo-code.  Thank you beforehand. Can $\sqrt{n} + \sqrt{m}$ be rational if neither $n,m$ are perfect squares? MicroSD card is set to Read-only state. How can I write data on it? Show that an operation being commutative is a structural property jQuery Validation plugin: disable validation for specified submit buttons I have a form with multiple fields that I'm validating (some with methods added for custom validation) with Jörn Zaeffere's excellent jQuery Validation plugin. How do you circumvent validation with specified submit controls (in other words, fire validation with some submit inputs, but do not fire validation with others)? This would be similar to ValidationGroups with standard ASP.NET validator controls.  My situation:  It's with ASP.NET WebForms, but you can ignore that if you wish. However, I am using the validation more as a "recommendation": in other words, when the form is submitted, validation fires but instead of a "required" message displaying, a "recommendation" shows that says something along the line of "you missed the following fields.... do you wish to proceed anyways?" At that point in the error container there's another submit button now visible that can be pressed which would ignore the validation and submit anyways. How to circumvent the forms .validate() for this button control and still post?  The Buy and Sell a House sample at  allows for this in order to hit the previous links, but it does so through creating custom methods and adding it to the validator. I would prefer to not have to create custom methods duplicating functionality already in the validation plugin.  The following is a shortened version of the immediately applicable script that I've got right now:  var container = $("#&lt;%= Form.ClientID %&gt; div.validationSuggestion");  $('#&lt;%= Form.ClientID %&gt;').validate({               errorContainer: container,     errorLabelContainer: $("ul",container),     rules: {         &lt;%= YesNo.UniqueID %&gt;: { required: true },         &lt;%= ShortText.UniqueID %&gt;: { required: true } // etc.      },     messages: {         &lt;%= YesNo.UniqueID %&gt;: 'A message.',         &lt;%= ShortText.UniqueID %&gt;: 'Another message.' // etc.     },     highlight: function(element, errorClass) {         $(element).addClass(errorClass);         $(element.form).find("label[for=" + element.id + "]").addClass(errorClass);         $(element.form).find("label[for=" + element.id + "]").removeClass("valid");     },     unhighlight: function(element, errorClass) {         $(element).removeClass(errorClass);         $(element.form).find("label[for=" + element.id + "]").removeClass(errorClass);         $(element.form).find("label[for=" + element.id + "]").addClass("valid");     },     wrapper: 'li' }); Add lines to cron from script Is there a way to add lines to a user's cron via script?  I usually do it using crontab -e, but I would like to automate this task with a shell script. How to determine whether a given Linux is 32 bit or 64 bit? When I type uname -a, it gives the following output.  Linux mars 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 i686 i686 i386 GNU/Linux   How can I know from this that the given OS is 32 or 64 bit?  This is useful when writing configure scripts, for example: what architecture am I building for?