Search Results

Search found 382 results on 16 pages for 'numerical'.

Page 3/16 | < Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >

  • Large sparse (stiff) ODE system needed for testing

    - by macydanim
    I hope this is the right place for this question. I have been working on a sparse stiff implicit ODE solver and have finished the code so far. I now tested the solver with the Van der Pol equation, and another stiff problem, which is of dimension 4. But to perform better tests I am searching for a bigger system. I'm thinking of the order N = 100...1000, if possible stiff and sparse. Does anybody have an example I could use? I really don't know where to search.

    Read the article

  • Typical Applications of Linear System Solver in Game Developemnt

    - by craftsman.don
    I am going to write a custom solver for linear system. I would like to survey the typical problems involved the linear system solving in games. So that I can custom optimization on these problems based on the shape of the matrix. currently I am focus on these problems: B-Spline editing (I use a linear solve to resolve the C0, C1, C2 continuity) Constraint in Simulation (especially Position-Constraint, cloth) Both of them are Banded Matrix. I want to hear about some other applications of a linear system in games. Thank you.

    Read the article

  • Integration error in high velocity

    - by Elektito
    I've implemented a simple simulation of two planets (simple 2D disks really) in which the only force is gravity and there is also collision detection/response (collisions are completely elastic). I can launch one planet into orbit of the other just fine. The collision detection code though does not work so well. I noticed that when one planet hits the other in a free fall it speeds backward and goes much higher than its original position. Some poking around convinced me that the simplistic Euler integration is causing the error. Consider this case. One object has a mass of 1kg and the other has a mass equal to earth. Say the object is 10 meters above ground. Assume that our dt (delta t) is 1 second. The object goes to the height of 9 meters at the end of the first iteration, 7 at the end of the second, 4 at the end of the third and 0 at the end of the fourth iteration. At this points it hits the ground and bounces back with the speed of 10 meters per second. The problem is with dt=1, on the first iteration it bounces back to a height of 10. It takes several more steps to make the object change its course. So my question is, what integration method can I use which fixes this problem. Should I split dt to smaller pieces when velocity is high? Or should I use another method altogether? What method do you suggest? EDIT: You can see the source code here at github:https://github.com/elektito/diskworld/

    Read the article

  • How is this number calculated?

    - by Hamid
    I have numbers; A == 0x20000000 B == 18 C == (B/10) D == 0x20000004 == (A + C) A and D are in hex, but I'm not sure what the assumed numeric bases of the others are (although I'd assume base 10 since they don't explicitly state a base. It may or may not be relevant but I'm dealing with memory addresses, A and D are pointers. The part I'm failing to understand is how 18/10 gives me 0x4. Edit: Code for clarity: *address1 (pointer is to address: 0x20000000) printf("Test1: %p\n", address1); printf("Test2: %p\n", address1+(18/10)); printf("Test3: %p\n", address1+(21/10)); Output: Test1: 0x20000000 Test2: 0x20000004 Test3: 0x20000008

    Read the article

  • Equation solver project

    - by Victor Barbu
    I would like to start a project destinated to students. My application has to solve any kind of equation, passed by the user as a string, exactly like in Matlab solve function. How shluld I do this? What programming language is the best for this purpose? Thanks in advance. P.S This is a screenshot made in Matlab. This is how I would like the user to insert and receive the answer: Another example:

    Read the article

  • HTML numerical to UTF

    - by Teneke
    How can i convert this $langClarContent = &# 1059.,ч.,и.,&# 1090.,&# 1077.,&# 1083.,Dokeos &# 1077., &# 1089.,&# 1080.,&# 1089.,&# 1090.,&# 1077.,&# 1084., &# 1079.,&# 1072., &# 1091.,&# 1087.,&# 1088.,&# 1072.,&# 1074.,&# 1091.,&# 1074.,&# 1072.,&# 1114.,е., &# 1089.,о., &# 1091.,&# 1095.,&# 1077.,&# 1114.,&# 1077., &# 1080., &# 1079.,&# 1085.,&# 1072.,е.,&# 1114.,&# 1077.,. &# 1058.,&# 1086.,&# 1112., &# 1080.,м., &# 1076.,&# 1086.,&# 1087.,&# 1091.,&# 1096.,&# 1090.,&# 1072., &# 1085.,&# 1072., у.,&# 1095 to an utf related answer like $langClarContent = Учител Dokeos е систем за управување со учење и знаење. Тој им допушта на уч

    Read the article

  • Fuzzy Search on Material Descriptions including numerical sizes & general descriptions of material t

    - by Kyle
    We're looking to provide a fuzzy search on an electrical materials database (i.e. conduit, cable, etc.). The problem is that, because of a lack of consistency across all material types, we could not split sizes into separate fields from the text description because some materials are rated by things other than size. I've attempted a combination of a full text search & a SQL CLR implementation of the Levenshtein search algorithm (for assistance in ranking), but my results are a little funky (i.e. they are not sorting correctly due to improper ranking). For example, if the search term is "3/4" ABCD Conduit", I'll might get back several irrelevant results in the following order: 1/2" Conduit 1/4" X 3/4" Cable 1/4" Cable Ties 3/4" DFC Conduit Tees 3/4" ABCD Conduit 3/4" Conduit I believe I've nailed the problem down to the fact that these two search algorithms do not factor in the relevance of punctuation & numeric. That is, in such a search, I'd expect the size to take precedence over any fuzzy match on the rest of the description, but my results don't reflect that. My question is: Can anyone recommend better search algorithms or different approaches that may be better suited for searching a combination of alphanumerics & punctuation characters?

    Read the article

  • Numerical precision of double type in Visual C++ 2008 Express debugger

    - by damik
    I'm using Visual C++ 2008 Express Edition and when i debug code: double x = 0.2; I see in debugging tooltip on x 0.20000000000000001 but: typedef numeric_limits< double > double_limit; int a = double_limit::digits10 gives me: a = 15 Why results in debugger are longer than maybe ? What is this strange precision based on ? My CPU is Intel Core 2 Duo T7100

    Read the article

  • Mobile web - hidden numerical input

    - by user499846
    Hi I am writing a web app (mainly iphone targeted) where the user has to enter their dob as part of the log in, I need this to be <input type = 'password'however I also want to enable the numeric section of the keyboard. I would usually change the type attr to 'number' however as this needs to be hidden I wondered if there was another way to activate the numeric pad Cheers! (ps I do not want to use any frameworks such as jquery on this)

    Read the article

  • numerical computation locks up ruby

    - by kolosy
    i'm trying to implement an id obfuscation scheme, with a simple hash borrowed elsewhere. i've added a method on the application helper: @@M_ID = 2**31-1 @@PRIME = 1580030173 @@PRIME_INVERSE = 59260789 # (calculated from MAXID and PRIME offline) def obfuscate_id(x) if x return ((x * @@PRIME) & @@M_ID) else x end end for some reason, whenever this is called, ruby locks up, and starts eating up disk space on my mac... like - gigs of it. any ideas?

    Read the article

  • Easy Slider 1.7 - Show any numerical slide as next

    - by Yourbudweiser
    I am using Easy Slider 1.7 - jQuery plugin and have made many modifications. My slider contains 7 slides, numeric navigation and next and previous arrows. The only problem is the numeric navigation. When you are on slide 1 and click slide 5, for example, all the slides scroll by, one-by-one. I am having trouble modifying the code so that whatever slide you are on, when you click another slide, it is the next one. Sample here: http://www.weiserwebworld.com/slider.html

    Read the article

  • Framework/tool for processing C++ unit tests with numerical output

    - by David Claridge
    Hi, I am working on a C++ application that uses computer vision techniques to identify various types of objects in a sequence of images. The (1000+) images have been hand-classified, so we have an XML file for each image containing a description of where the objects are actually located in the images. I would like to know if there is a testing framework that can understand/graph results from tests that are numeric, in this case some measure of the error in the program's classification of the images, rather than just pass/fail style unit tests. We would like to use something like CDash/CTest for running these automated tests, and viewing over time how improvements to the vision algorithms are causing the images to be more correctly classified. Does anyone know of a tool/framework that can do this?

    Read the article

  • Django: ordering numerical value with order_by

    - by h3
    I'm in a situation where I must output a quite large list of objects by a CharField used to store street addresses. My problem is, that obviously the data is ordered by ASCII codes since it's a Charfield, with the predictable results .. it sort the numbers like this; 1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 20, 21.... Now the obvious step would be to change the Charfield the proper field type (IntegerField let's say), however it cannot work since some address might have apartments .. like "128A". I really don't know how I can order this properly ..

    Read the article

  • str_replace between two numerical strings

    - by user330840
    Another problem with str_replace, I would like to change the following $title data into URL by taking the $string between number in the beginning and after dash (-) Chicago's Public Schools - $10.3M New Jersey - $3M Michigan: Public Health - $1M The desire output is: chicago-public-school new-jersey michigan-public-health PHP code I am using $title = ucwords(strtolower(strip_tags(str_replace("1: ","",$title)))); $x=1; while($x <= 10) { $title = ucwords(strtolower(strip_tags(str_replace("$x: ","",$title)))); $x++; } $link = preg_replace('/[<>()!#?:.$%\^&=+~`*&#233;"\']/', '',$title); $money = str_replace(" ","-",$link); $link = explode(" - ",$link); $link = preg_replace(" (\(.*?\))", "", $link[0]); $amount = preg_replace(" (\(.*?\))", "", $link[1]); $code_entities_match = array( '&#39;s' ,'&quot;' ,'!' ,'@' ,'#' ,'$' ,'%' ,'^' ,'&' ,'*' ,'(' ,')' ,'+' ,'{' ,'}' ,'|' ,':' ,'"' ,'<' ,'>' ,'?' ,'[' ,']' ,'' ,';' ,"'" ,',' ,'.' ,'_' ,'/' ,'*' ,'+' ,'~' ,'`' ,'=' ,' ' ,'---' ,'--','--'); $code_entities_replace = array('' ,'-' ,'-' ,'' ,'' ,'' ,'-' ,'-' ,'' ,'' ,'' ,'' ,'' ,'' ,'' ,'-' ,'' ,'' ,'' ,'' ,'' ,'' ,'' ,'' ,'' ,'-' ,'' ,'-' ,'-' ,'' ,'' ,'' ,'' ,'' ,'-' ,'-' ,'-','-'); $link = str_replace($code_entities_match, $code_entities_replace, $link); $link = strtolower($link); Unfortunately the result I got: -chicagoamp9s-public-school 2-new-jersey 3-michigan-public-health Anyone has a better solution for this? Thanks guys! (the &#39; changed into amp9 - wonder why?)

    Read the article

  • Convert complex numerical array to associative array [PHP]

    - by user1500412
    I have an array data that look like this : Array ( [0] => Array ( [0] => Name: [1] => John W. [2] => Registration ID: [3] => 36 ) [1] => Array ( [0] =>Age: [1] => 35 [2] => Height: [3] => 5'11" ) [3] => Array ( [0] => Sex: [1] => M [2] => Weight: [3] => 200lbs ) [4] => Array ( [0] => Address ) [5] => Array ( [0] => 6824 crestwood dr delphi, IN 46923 )) And I want to convert it to associative array like this : Array( ['Name']=> John W. ['Registration ID']=> 36 ['Age']=> 35 ['Height'] => 5'11'' ['Sex']=>M ['Weight']=>200lbs ['Address']=>6824 crestwood dr delphi, IN 46923 ) I have no idea at all how to do this, since the supposed to be array column header were also in sequence, so it makes difficult to convert this array. Any help I appreciate, thx.

    Read the article

  • Using logarithms to normalize a vector to avoid overflow

    - by muscicapa
    http://stackoverflow.com/questions/2293762/problem-with-arithmetic-using-logarithms-to-avoid-numerical-underflow-take-2 Having seen the above and having seen softmax normalization I was trying to normalize a vector while avoiding overflow - that is (x1 x2 x3 x4 ... xn) the normalized form for me has the sum of squares as 1.0 So what I thought of doing is s=(2*log(x1)+2*log(x2)+...+2*log(xn))/2 so the two factor can be taken off and finally the normalized vector is exp(log(x1)-s), , ..., exp(log(xn)-s) but I am evidently doing something wrong here, what?

    Read the article

  • C or Ada for engineering computations?

    - by yCalleecharan
    Hi,as an engineer I currently use C to write programs dealing with numerical methods. I like C as it's very fast. I don't want to move to C++ and I have been reading a bit about Ada which has some very good sides. I believe that much of the software in big industries have been or more correctly were written in Ada. I would like to know how C compares with Ada. Is Ada fast as C? I understand that no language is perfect but I would like to know if Ada was designed for scientific computing. Thanks a lot...

    Read the article

  • Efficiency of manually written loops vs operator overloads (C++)

    - by Sagekilla
    Hi all, in the program I'm working on I have 3-element arrays, which I use as mathematical vectors for all intents and purposes. Through the course of writing my code, I was tempted to just roll my own Vector class with simple +, -, *, /, etc overloads so I can simplify statements like: for (int i = 0; i < 3; i++) r[i] = r1[i] - r2[i]; // becomes: r = r1 - r2; Which should be more or less identical in generated code. But when it comes to more complicated things, could this really impact my performance heavily? One example that I have in my code is this: Manually written version: for (int j = 0; j < 3; j++) { p.vel[j] = p.oldVel[j] + (p.oldAcc[j] + p.acc[j]) * dt2 + (p.oldJerk[j] - p.jerk[j]) * dt12; p.pos[j] = p.oldPos[j] + (p.oldVel[j] + p.vel[j]) * dt2 + (p.oldAcc[j] - p.acc[j]) * dt12; } Using a Vector class with operator overloads: p.vel = p.oldVel + (p.oldAcc + p.acc) * dt2 + (p.oldJerk - p.jerk) * dt12; p.pos = p.oldPos + (p.oldVel + p.vel) * dt2 + (p.oldAcc - p.acc) * dt12; I am compiling my code for maximum possible speed, as it's extremely important that this code runs quickly and calculates accurately. So will me relying on my Vector's for these sorts of things really affect me? For those curious, this is part of some numerical integration code which is not trivial to run in my program. Any insight would be appreciated, as would any idioms or tricks I'm unaware of.

    Read the article

  • How should I deal with floating numbers that numbers that can get so small that the become zero

    - by Tristan Havelick
    So I just fixed an interesting bug in the following code, but I'm not sure the approach I took it the best: p = 1 probabilities = [ ... ] # a (possibly) long list of numbers between 0 and 1 for wp in probabilities: if (wp > 0): p *= wp # Take the natural log, this crashes when 'probabilites' is long enough that p ends up # being zero try: result = math.log(p) Because the result doesn't need to be exact, I solved this by simply keeping the smallest non-zero value, and using that if p ever becomes 0. p = 1 probabilities = [ ... ] # a long list of numbers between 0 and 1 for wp in probabilities: if (wp > 0): old_p = p p *= wp if p == 0: # we've gotten so small, its just 0, so go back to the smallest # non-zero we had p = old_p break # Take the natural log, this crashes when 'probabilites' is long enough that p ends up # being zero try: result = math.log(p) This works, but it seems a bit kludgy to me. I don't do a ton of this kind of numerical programming, and I'm not sure if this is the kind of fix people use, or if there is something better I can go for.

    Read the article

  • Using Taylor Series to Avoid Loss of Precision

    - by Zachary
    I'm trying to use Taylor series to develop a numerically sound algorithm for solving a function. I've been at it for quite a while, but haven't had any luck yet. I'm not sure what I'm doing wrong. The function is f(x)=1 + x - sin(x)/ln(1+x) x~0 Also: why does loss of precision even occur in this function? when x is close to zero, sin(x)/ln(1+x) isn't even close to being the same number as x. I don't see where significance is even being lost. In order to solve this, I believe that I will need to use the Taylor expansions for sin(x) and ln(1+x), which are x - x^3/3! + x^5/5! - x^7/7! + ... and x - x^2/2 + x^3/3 - x^4/4 + ... respectfully. I have attempted to use like denominators to combine the x and sin(x)/ln(1+x) components, and even to combine all three, but nothing seems to work out correctly in the end. Any help is appreciated.

    Read the article

  • Open source alternative to MATLAB's fmincon function?

    - by dF
    Is there an open-source alternative to MATLAB's fmincon function for constrained linear optimization? I'm rewriting a MATLAB program to use Python / NumPy / SciPy and this is the only function I haven't found an equivalent to. A NumPy-based solution would be ideal, but any language will do.

    Read the article

< Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >