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Search found 3425 results on 137 pages for 'polynomial math'.

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• Getting pixel averages of a vector sitting atop a bitmap...

  - by user346511

  I'm currently involved in a hardware project where I am mapping triangular shaped LED to traditional bitmap images. I'd like to overlay a triangle vector onto an image and get the average pixel data within the bounds of that vector. However, I'm unfamiliar with the math needed to calculate this. Does anyone have an algorithm or a link that could send me in the right direction? (I tagged this as Python, which is preferred, but I'd be happy with the general algorithm!) I've created a basic image of what I'm trying to capture here: http://imgur.com/Isjip.gif

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• Does this variable need to be declared volatile?

  - by titaniumdecoy

  Does the out variable in the MyThread class need to be declared volatile in this code or will the "volatility" of the stdout variable in the ThreadTest class carry over? import java.io.PrintStream; class MyThread implements Runnable { int id; PrintStream out; // should this be declared volatile? MyThread(int id, PrintStream out) { this.id = id; this.out = out; } public void run() { try { Thread.currentThread().sleep((int)(1000 * Math.random())); out.println("Thread " + id); } catch (InterruptedException e) { e.printStackTrace(); } } } public class ThreadTest { static volatile PrintStream stdout = System.out; public static void main(String[] args) { for (int i = 0; i < 10; i++) { new Thread(new MyThread(i, stdout)).start(); } } }

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• Split a map using Groovy

  - by Tihom

  I want to split up a map into an array of maps. For example, if there is a map with 25 key/value pairs. I want an array of maps with no more than 10 elements in each map. How would I do this in groovy? I have a solution which I am not excited about, is there better groovy version: static def splitMap(m, count){ if (!m) return def keys = m.keySet().toList() def result = [] def num = Math.ceil(m?.size() / count) (1..num).each { def min = (it - 1) * count def max = it * count > keys.size() ? keys.size() - 1 : it * count - 1 result[it - 1] = [:] keys[min..max].each {k -> result[it - 1][k] = m[k] } } result } m is the map. Count is the max number of elements within the map.

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• How can I rotate an image using Java/Swing and then set its origin to 0,0?

  - by JT

  I'm able to rotate an image that has been added to a JLabel. The only problem is that if the height and width are not equal, the rotated image will no longer appear at the JLabel's origin (0,0). Here's what I'm doing. I've also tried using AffineTransform and rotating the image itself, but with the same results. Graphics2D g2d = (Graphics2D)g; g2d.rotate(Math.toRadians(90), image.getWidth()/2, image.getHeight()/2); super.paintComponent(g2d); If I have an image whose width is greater than its height, rotating that image using this method and then painting it will result in the image being painted vertically above the point 0,0, and horizontally to the right of the point 0,0.

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• Direct video card access

  - by icemanind

  Guys, I am trying to write a class in C# that can be used as a direct replacement for the C# Bitmap class. What I want to do instead though is perform all graphic functions done on the bitmap using the power of the video card. From what I understand, functions such as DrawLine or DrawArc or DrawText are primitive functions that use simple cpu math algorithms to perform the job. I, instead, want to use the graphics card cpu and memory to do these and other advanced functions, such as skinning a bitmap (applying a texture) and true transparancy. My problem is, in C#, how do I access direct video functions? Is there a library or something I need?

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• dose not name a type error in c++

  - by user985316

  #include <math.h> #include <stdlib.h> #include <stdio.h> #include <vector> #define IE 40 #define JE 40 #define KE 40 #define ia 7 #define ja 7 #define ka 7 #define NFREQS 3 using namespace std; main() float l,m,n,i,j,k,ic,jc,kc,nsteps,n_pml; float ddx,dt,T,epsz,muz,pi,eaf,npml; int ib,jb,kb; . . . . ic=IE*0.5 ; jc=JE*0.5 ; ....'ic'dose not name a type. ....'jc'dose not name a type.

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• Is webserver bandwith the entire HTTP Request/Responce?

  - by Lienau

  Just a quick question. I'm making a web application where C++ communicates with a php script over HTTP Requests/Response. The data being set back and forth is quite small ~36 bytes. But I plan to have many computers connected, contacting the server quite often. I did the math, and I could potentially have gigabytes of data transfer a month. This isn't too much of problem, but it would be if the bandwidth included the request/response headers the request size would be about ~560 bytes. That's about 16x more bandwidth than I was planning... That would be a lot. If if any one knew how host determine bandwidth and could share, that'd be great. Thanks.

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• Integers in JavaScript

  - by muntoo

  I'm a beginner to Javascript so forgive me if I sound dumb because I learned some Javascript from W3Fools (which are really difficult tutorials - they don't explain anything I want to know, but everything I probably can guess from my experience with C++). I may be switching over to MDN, but if you can recommend any other tutorials, that be great. Anyways, so here's my question: I just read a few lines of this, and apparently: Numbers in JavaScript are "double-precision 64-bit format IEEE 754 values", according to the spec. This has some interesting consequences. There's no such thing as an integer in JavaScript, so you have to be a little careful with your arithmetic if you're used to math in C or Java. I've already seen that there are few of the data types (for variables) I'm used to from C++. But I didn't expect all numbers to automatically be floats. Isn't there any way to use integers, not float? Will a future version of JavaScript support ints?

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• Finding the angle of a fleeing dodo.

  - by donthackmyacc

  I'm coding some critter AI for a game i am working on for my Unity 3D project. I have no programming background and have been stumbling through this using tutorials and other peoples scripts. My problem is that i want my critter to run directly away from the player when the player kicks it. I need the dodo to run directly away from the player when kicked, and i dont know the math nor the syntax to calculate that angle. They are two characters moving independently through worldspace. Here is what i got so far: waypoint = (fleeWP.transform.position); transform.LookAt(Vector3(waypoint.x, transform.position.y, waypoint.z)); transform.Translate (Vector3.forward * speed * Time.deltaTime); This currently makes the critter move towards the waypoint, rather than away. I might be attacking this all wrong. Please chastise me.

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• Setting tabindex in dynamic table vertically then horizontally

  - by Wil

  I have a page that is currently generating dynamically created textboxes in a table format. The users are requesting that the tab order be changed from horizontal-vertical to vertical-horizontal. I know that you can use the tabindex attribute to control the tab ordering, but I can't for the life of me figure out the right way to get the sequential number properly for the textboxes. I guess this is more of a math question than anything else! FYI, the textboxes are made while looping two different collections. First collection looped to make the rows, for each row, second collection (which is a property of the first collection objects) is looped to create the columns. Any help would be greatly appreciated. Thanks!

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• Script Speed vs Memory Usage

  - by Doug Neiner

  I am working on an image generation script in PHP and have gotten it working two ways. One way is slow but uses a limited amount of memory, the second is much faster, but uses 6x the memory . There is no leakage in either script (as far as I can tell). In a limited benchmark, here is how they performed: -------------------------------------------- METHOD | TOTAL TIME | PEAK MEMORY | IMAGES -------------------------------------------- One | 65.626 | 540,036 | 200 Two | 20.207 | 3,269,600 | 200 -------------------------------------------- And here is the average of the previous numbers (if you don't want to do your own math): -------------------------------------------- METHOD | TOTAL TIME | PEAK MEMORY | IMAGES -------------------------------------------- One | 0.328 | 540,036 | 1 Two | 0.101 | 3,269,600 | 1 -------------------------------------------- Which method should I use and why? I anticipate this being used by a high volume of users, with each user making 10-20 requests to this script during a normal visit. I am leaning toward the faster method because though it uses more memory, it is for a 1/3 of the time and would reduce the number of concurrent requests.

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• Why are there so many floats in the Android API?

  - by Brian

  The default floating point type in Java is the double. If you hard code a constant like 2.5 into your program, Java makes it a double automatically. When you do an operation on floats or ints that could potentially benefit from more precision, the type is 'promoted' to a double. But in the Android API, everything seems to be a float from sound volumes to rectangle coordinates. There's a structure called RectF used in most drawing; the F is for float. It's really a pain for programmers who are casting promoted doubles back to (float) pretty often. Don't we all agree that Java code is messy and verbose enough as it is? Usually math coprocessors and accelerators prefer double in Java because it corresponds to one of the internal types. Is there something about Android's Dalvik VM that prefers floats for some reason? Or are all the floats just a result of perversion in API design?

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• Algorithm to emulate mouse movement as a human does?

  - by Eye of Hell

  Hello I need to test a software that treats some mouse movements as "gestures". For such a task I need to emulate mouse movement from point A to point B, not in straight line, but as a real mouse moves - with curves, a bit of jaggedyness etc. Is there any available solution (algorithm/code itself, not a library/exe) that I can use? Of course I can write some simple sinusoidal math by myself, but this would be a very crude emulation of a human hand leading a mouse. Perhaps such a task has been solved already numerous times, and I can just borrow an existing code? :)

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• Bit Flipping in Hex

  - by freyrs

  I have an 8 digit hexadecimal number of which I need certain digits to be either 0 or f. Given the specific place of the digits is there a quick way to generate the hex number with those places "flipped" to f. For example: flip_digits(1) = 0x000000f flip_digits(1,2,4) = 0x0000f0ff flip_digits(1,7,8) = 0xff00000f I'm doing this on an embedded device so I can't call any math libraries, I suspect it can be done with just bit shifts but I can't quite figure out the method. Any sort of solution (Python, C, Pseudocode) will work. Thanks in advance.

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• What to beware of reading old Numarray tutorials and examples?

  - by DarenW

  Python currently uses Numpy for heavy duty math and image processing. The earlier Numeric and Numarray are obsolete, but still today there are many tutorials, notes, sample code and other documentation using them. Some of these cover special topics of interest, some are well written but haven't been updated or replaced, or are otherwise of use. Quite a bit is the same between Numeric, Numarray and Numpy, so I usually get good mileage out these older docs. Ocassionaly, though, I run into a line of code that results in error. Not often enough to remember how to get around it, but usually I figure it out at the cost of some time. What are the main things to watch out for when relying on such older documentation for current Numpy use? Is there a list of how to translate the differences that exist?

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• How should I compile boost library in a small project?

  - by Vincenzo

  I have a small project where I need just part of boost library, boost::regex in particular. This is what I've done so far: /include /boost /regex /math .. 189 dirs, files, etc. /lib /boost-regex c_regex_traits.cpp cpp_regex_traits.cpp .. ~20 .cpp files myprog.cpp In my Makefile I compile all boost-regex .cpp files one by one, producing .obj files. Next, I'm building my project by means of compiling myprog.cpp together with all that .obj files from /lib/boost/regex. The question is whether I'm doing everything correct? The size of my output file is rather big (~3.5Mb), while my code is extremely small (10 lines).

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• How can I maximally partition a set?

  - by Gregory Higley

  I'm trying to solve one of the Project Euler problems. As a consequence, I need an algorithm that will help me find all possible partitions of a set, in any order. For instance, given the set 2 3 3 5: 2 | 3 3 5 2 | 3 | 3 5 2 | 3 3 | 5 2 | 3 | 3 | 5 2 5 | 3 3 and so on. Pretty much every possible combination of the members of the set. I've searched the net of course, but haven't found much that's directly useful to me, since I speak programmer-ese not advanced-math-ese. Can anyone help me out with this? I can read pretty much any programming language, from BASIC to Haskell, so post in whatever language you wish.

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• Should I use implicit conversions to enforce preconditions?

  - by Malvolio

  It occurs to me that I could use use implicit conversions to both announce and enforce preconditions. Consider this: object NonNegativeDouble { implicit def int2nnd(d : Double) : NonNegativeDouble = new NonNegativeDouble(d) implicit def nnd2int(d : NonNegativeDouble) : Double = d.v def sqrt(n : NonNegativeDouble) : NonNegativeDouble = scala.math.sqrt(n) } class NonNegativeDouble(val v : Double ) { if (v < 0) { throw new IllegalArgumentException("negative value") } } object Test { def t1 = { val d : Double = NonNegativeDouble.sqrt(3.0); printf("%f\n", d); val n : Double = NonNegativeDouble.sqrt(-3.0); } } Ignore for the moment the actual vacuity of the example: my point is, the subclass NonNegativeDouble expresses the notion that a function only takes a subset of the entire range of the class's values. First is this: A good idea, a bad idea, or an obvious idea everybody else already knows about Second, this would be most useful with basic types, like Int and String. Those classes are final, of course, so is there a good way to not only use the restricted type in functions (that's what the second implicit is for) but also delegate to all methods on the underlying value (short of hand-implementing every delegation)?

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• Interesting AS3 hash situation. Is it really using strict equality as the documentation says?

  - by Triynko

  AS3 Code: import flash.utils.Dictionary; var num1:Number = Number.NaN; var num2:Number = Math.sqrt(-1); var dic:Dictionary = new Dictionary( true ); trace(num1); //NaN trace(num2); //NaN dic[num1] = "A"; trace( num1 == num2 ); //false trace( num1 === num2 ); //false trace( dic[num1] ); //A trace( dic[num2] ); //A Concerning the key comparison method... "The Dictionary class lets you create a dynamic collection of properties, which uses strict equality (===) for key comparison. When an object is used as a key, the object's identity is used to look up the object, and not the value returned from calling toString() on it." If Dictionary uses strict equality, as the documentation states, then how is it that num1 === num2 is false, and yet dic[num1] resolves to the same hash slot as dic[num2]?

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• checking whether 4 points in a plane define a square ??

  - by osabri

  how to check whether 4 points in the plane define a square? what's the function which given a point and a value of the area of a square as input parameters returns four squares(define a corresponding type) with sides parallel to the x axis and y axis this how i start: #include <stdio.h> #include<math.h> struct point{ float x; float y; } typedef struct point POINT; struct square{ struct point p1; struct point p2; struct point p3; struct point p4; } typedef struct square SQUARE; int main() { int point; printf("point coordinate"); printf("\n\n"); printf("enter data\n");

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• Malicious javascript code in my website

  - by Depami

  I found this code in my website sourcecode: var _0xd28d=["\x5F\x30\x78\x33\x32\x6C\x73\x6A\x39","\x5F\x78\x6C\x74","\x5F\x78\x38\x66\x6B\x63\x33","\x66\x6C\x6F\x6F\x72","\x72\x61\x6E\x64\x6F\x6D","\x6C\x65\x6E\x67\x74\x68"];var _0x9ae4=[_0xd28d[0],12,_0xd28d[1],_0xd28d[2],2,31,Math,_0xd28d[3]];var _0xcd6e=[_0x9ae4[5],_0x9ae4[0],_0x9ae4[_0x9ae4[4]],_0x9ae4[3],4,_0xd28d[4]];var _0xr6g0={};_0xr6g0[_0xcd6e[2]]=0;_0xr6g0[_0x9ae4[4]]=function (){var _0x4c68x4={};_0x4c68x4[_0xd28d[0]]=_0x9ae4[0];do{_0x4c68x4[_0x9ae4[0]]+=_0x4c68x4[_0xd28d[0]][_0x9ae4[6][_0x9ae4[7]](_0x9ae4[6][_0xcd6e[5]]()*_0x4c68x4[_0xd28d[0]][_0xd28d[5]])];} while(_0x4c68x4[_0xd28d[0]][_0xd28d[5]]<_0xcd6e[0]);;_0x4c68x4[_0x4c68x4[_0x9ae4[0]]]=function (){_0xr6g0[_0xcd6e[2]]++;_0xr6g0[_0xcd6e[2]]%=_0x9ae4[1];return _0x4c68x4[_0x4c68x4[_0x9ae4[0]]];} ;return _0x4c68x4[_0x4c68x4[_0xcd6e[1]]];} ;_0xr6g0[_0x9ae4[_0xcd6e[4]]]()()()()()()()()()()()()()()()(); I was wondering, what is it?

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• Operational Transformation library?

  - by gamers2000

  I'm looking for a library that would allow me to synchronize text in real-time between multiple users (ala Google Docs). I've stumbled upon Operational Transformation, which seems to fit my needs. Having said that, I understand the gist of OT, but not the math nor implementation of OT. Thus, I was wondering if there was a drag'n'drop Javascript library that would hook into a text area, generate the transforms, then allow me to apply those transformations onto another client? (I've gotten the Etherpad source, but I can't make head or tails out of it. If anyone could point out how to leverage on Etherpad's OT implementation, that'll be great too!)

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• LINQ Equivalent query

  - by GilliVilla

  I have a List<string> List<string> students; students.Add("123Rob"); students.Add("234Schulz"); and a Dictionary<string,string> Dictionary<string, string> courses = new Dictionary<string, string>(); courses .Add("Rob", "Chemistry"); courses .Add("Bob", "Math"); courses .Add("Holly", "Physics"); courses .Add("Schulz", "Botany"); My objective now is to get a List with the values - {Chemistry,Botany} . In other words, I am trying to get the LINQ equivalent of select value from [courses] where [courses].key in ( select [courses].key from courses,students where [students].id LIKE '%courses.key%' ) How should the LINQ query be framed?

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• Simple 2 way encryption for C#

  - by Matt Dawdy

  I'm looking for very simple encrypt and decrypt functionality for some data. It's not mission critical. I need something to keep honest people honest, but something a little stronger than ROT13 or Base64. I'd prefer something that is already included in the .Net framework 2.0 so I don't have to worry about any external dependencies. Pre-emptive EDIT: I really don't want to have to mess around with public/private keys, etc. I don't know much about encryption, but I do enough to know that anything I wrote would be less than worthless...in fact, I'd probably screw up the math and make it trivial to crack.

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• calculate next line numbers

  - by osomanden

  Weird question I guess.. But I am not very math wiz - soo here goes.. I am trying to create a patterne (or variable patterns based on selection) based on x and y numbers (2 rows and 4 columns) and the direction of the counting of x numbers like: 1-2-3-4 5-6-7-8 That one is easy, when number of x-columns is reached, next line and continue x count. But with eg. this one (still 2 rows and 4 columns): 1-2-3-4 8-7-6-5 upsie.. what if it is eg. 3++ rows and still 4 columns? 1-2-3-4 8-7-6-5 9-10-11-12 what would be the formula for this - or other possible variations (teaser for variations): 9-10-11-12 8-7-6-5 1-2-3-4 or reversed

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