Main Archive Specials Wiki | FAQ Links Submit Forum

 Fast in-place Walsh-Hadamard TransformType : wavelet transformReferences : Posted by Timo H TossavainenNotes : IIRC, They're also called walsh-hadamard transforms. Basically like Fourier, but the basis functions are squarewaves with different sequencies. I did this for a transform data compression study a while back. Here's some code to do a walsh hadamard transform on long ints in-place (you need to divide by n to get transform) the order is bit-reversed at output, IIRC. The inverse transform is the same as the forward transform (expects bit-reversed input). i.e. x = 1/n * FWHT(FWHT(x)) (x is a vector)Code : void inline wht_bfly (long& a, long& b) { long tmp = a; a += b; b = tmp - b; } // just a integer log2 int inline l2 (long x) { int l2; for (l2 = 0; x > 0; x >>=1) { ++ l2; } return (l2); } //////////////////////////////////////////// // Fast in-place Walsh-Hadamard Transform // //////////////////////////////////////////// void FWHT (std::vector& data) { const int log2 = l2 (data.size()) - 1; for (int i = 0; i < log2; ++i) { for (int j = 0; j < (1 << log2); j += 1 << (i+1)) { for (int k = 0; k < (1< { wht_bfly (data [j + k], data [j + k + (1< } } } }

 CommentsAdded on : 29/01/03 by i_arslan[ AT ]gmx[ DOT ]netComment :     How can i implement this code in matlab ?Added on : 13/04/03 by Noor98z[ AT ]hotmail[ DOT ]comComment : Need an Implemtation of Walsh Transform Matlab Code              Added on : 14/04/03 by ambadarneh[ AT ]hotmail[ DOT ]comComment :    well sir nice work ,but how can i get the code in MATLAB . could you help me please. thank you yours sicerly Ala' Badarneh Jordan University of Science & Technology Biomedical Engineering Department           Added on : 06/04/04 by msalharbi[ AT ]hotmail[ DOT ]comComment : Noor98z@hotmail.com .... need implementation of walsh transform Matlab code and me need.Added on : 18/06/04 by fahira10[ AT ]hotmail[ DOT ]comComment : Dear sir, your job is amazing! I was just searching for a WHT program but I did not find any Matlab command for that. Is there a way to implement that code in Matlab? Best regardsAdded on : 22/11/04 by z_xf[ AT ]sdu[ DOT ]edu[ DOT ]cnComment :    nice work ,but how can i get the code in MATLAB . could you help me please.thank you! yours sicerly  zhang          Added on : 11/01/05 by (1< - ??????????????????????Comment : What is symbols "(1<" in C++; I dont know this symbols. Please help me.Added on : 24/01/05 by beeka at beeka dot orgComment : You might want to look at the page source. This shows the "(1<" was trying to be "(1 << i)" (I hope the browser leaves that one alone): for (int k = 0; k < (1 << i); ++k) {   wht_bfly (data [j + k], data [j + k + (1 << i)]); }Added on : 25/01/05 by bcreado[ AT ]hotmail[ DOT ]comComment :      well sir nice work ,but how can i get the code in MATLAB . could you help me please         Added on : 20/02/05 by anonymousComment : Hello, I just thought I would let you know that I do not want MatLab code for this. Thank you. Added on : 04/01/07 by tired_of_morons[ AT ]gmail[ DOT ]comComment : FOR CRYING OUT LOUD!! IMPLEMENT IT YOURSELF IN MATLAB! OR MAYBE, JUST MAYBE, IF YOU REQUEST FOR MATLAB CODE TEN TIMES MORE, YOU'LL GET IT... NOT! "Most people are amazing. Just not in a positive sense..." - unknown Added on : 04/01/07 by nobody[ AT ]nowhere[ DOT ]comComment : What the hell is MATLAB anyway?   Added on : 05/01/07 by scoofy[ AT ]inf[ DOT ]elte[ DOT ]huComment : MATLAB guys: Have you ever tried the google search "fast walsh hadamard matlab"? If yes, look at the first link.              Added on : 29/08/07 by debonair_swathi[ AT ]yahoo[ DOT ]co[ DOT ]inComment :        i need program in c to generate a hadamard matrix of any order       Added on : 07/09/07 by debonair_swathi[ AT ]yahoo[ DOT ]co[ DOT ]inComment :    sir i need program in c to get the walsh matrix of any order to use as a coding tecchnique in  CDMA  .can u email it to me          Added on : 04/11/07 by anonymousComment : Lend a hand and they grab your shoulder...      Added on : 19/05/09 by bob[ AT ]yahoob[ DOT ]comComment : If you can't convert a few lines of 'c' into to another language, then you must be mad, or lazy, or both.

 Add your own comment Comments are displayed in fixed width, no HTML code allowed! Email: Comment: Are you human?

Site created and maintained by Bram
Graphic design by line.out | Server sponsered by fxpansion