Matlab's fftw returns nothing?

Started by Vista in comp.dsp10 years ago 1 reply

Hi all, Matlab command "fftw" supposedly should return something, as described in the following help document. But when I tried these command...

Hi all, Matlab command "fftw" supposedly should return something, as described in the following help document. But when I tried these command examples, nothing happened, i.e. "fftw" returned nothing. What might be the problem? Thanks ------------------------------------------------------------------------------------------ > > help fftw FFTW Interface to FFTW library run-time a


ANN: beta version of FFTW now available

Started by Anonymous in comp.dsp11 years ago 1 reply

I just noticed a new beta version of FFTW is available at www.fftw.org. I look forward to trying it. I am building it as I write this. Thanks...

I just noticed a new beta version of FFTW is available at www.fftw.org. I look forward to trying it. I am building it as I write this. Thanks for all your hard work Steven & Mateo. Considering how often FFTW is discussed on this newsgroup, I thought it worthy of an announcement. If you currently use FFTW, you may want to be a good netizen and download the beta to get a sneak preview o...


FFTW in Visual Studio C++

Started by karenying in comp.dsp12 years ago 2 replies

I want to use FFTW in visual Studio 6.0 , and I have downloaded the FFTW 3.0.1 static library files...

I want to use FFTW in visual Studio 6.0 , and I have downloaded the FFTW 3.0.1 static library files from http://www.ece.cmu.edu/~franzf/fftw.org/. However, I cannot run the program as expected ? Did i do anything wrong ? I did not download the FFTW 3.0.1 VisualStudio 6.0 project files (require Intel C++ compiler installed) because there is compliation error when i build it and i cannot s...


[ANNOUNCE] FFTW-3.1.3 released

Started by Anonymous in comp.dsp9 years ago

Dear FFTW users, we are pleased to announce the availability of FFTW 3.1.3, which you can download from the web page: ...

Dear FFTW users, we are pleased to announce the availability of FFTW 3.1.3, which you can download from the web page: http://fftw.org/download.html This release fixes a bug that causes incorrect results to be computed in programs that use both REDFT11 (a.k.a. DCT-IV) and RODFT11 (a.k.a. DST-IV) at the same time. Because of the potential for incorrect results, users of FFTW 3.1...


[FFTW] SSE is not used?

Started by in comp.dsp10 years ago 7 replies

Hi, any FFTW experts reading this? :-) I'm using FFTW. But i cannot measure any difference between runs with FFTW_NO_SIMD and...

Hi, any FFTW experts reading this? :-) I'm using FFTW. But i cannot measure any difference between runs with FFTW_NO_SIMD and without. I'm trying to do in-place DFT, with plans created like this: fftw_complex *buf0 = fftw_malloc(...) fftw_plan_dft_1d(N, buf0, buf0, FFTW_FORWARD, 0) FFTW has been compiled with SSE and SSE2 support. I'm using double-precision. Any ideas how ca...


Double precision in FFTW

Started by chiraag in comp.dsp8 years ago 4 replies

Hi all, I am relatively new to using FFTW.. I have been using FFTW to take fft for a few complex matrices. My problem is that I am not gettign...

Hi all, I am relatively new to using FFTW.. I have been using FFTW to take fft for a few complex matrices. My problem is that I am not gettign the same values in Matlab and C++, the values seem to be differing after the sixth or seventh significant bit. When we use fftw_plan are we using double precision by default or do we have to use fftwl_plan[so on for all the fftw calls]?? I have been tryi...


Problems using fftw, fftw_free

Started by in comp.dsp12 years ago 2 replies

Hello, It's my first post and so I've searched some topics about fftw, trying not to ask something alredy answered and I didn't find anything...

Hello, It's my first post and so I've searched some topics about fftw, trying not to ask something alredy answered and I didn't find anything about it, so I'd like to ask your help about using fftw... I'm a borland c++ builder user (bc++ 5) and fftw runs smooth and fast calculating the fft of my real data (audio data) ... but I get problems when I try to deallocate the fft output buffer I crea...


Zero padding in FFTW

Started by Peng Yu in comp.dsp13 years ago 5 replies

Dear All, I want to do zero padding of of the data and than do fft by FFTW(www.fftw.org). The dummiest way is to make an array which has...

Dear All, I want to do zero padding of of the data and than do fft by FFTW(www.fftw.org). The dummiest way is to make an array which has more elements than the data set size. However, it takes more memory space and more computation time. I'm wondering if there is a way to tell FFTW do zero padding automatical and compute the fft. Best wishes, Peng


FFTW 3.1 available, new benchmarks

Started by Matteo Frigo in comp.dsp12 years ago 3 replies

We are pleased to announce the availability of FFTW 3.1, which you can download from the web page. http://fftw.org/download.html In...

We are pleased to announce the availability of FFTW 3.1, which you can download from the web page. http://fftw.org/download.html In addition, we have updated our fft benchmark pages with results from recent machines. Cordially, Matteo Frigo Steven G. Johnson Changes since FFTW 3.0.1: * Faster FFTW_ESTIMATE planner. * New (faster) algorithm for REDFT00/RODFT00 (type-I D...


fftw-int.h and fftw scope errors

Started by climatechange in comp.dsp9 years ago 2 replies

Hi, When i compile the test test_main.c in the tests folder of FFTW I get an error saying adatta@imaa-caribou /usr/src/fftw-2.1.5/tests $...

Hi, When i compile the test test_main.c in the tests folder of FFTW I get an error saying adatta@imaa-caribou /usr/src/fftw-2.1.5/tests $ g++ test_main.c test_main.c:25:22: fftw-int.h: No such file or directory In file included from test_main.c:33: test_main.h:87: warning: `compute_error_complex' initialized and declared `exter n' test_main.h:87: error: `fftw_complex' was not declared ...


FFTW For VisualDSP

Started by shachris23 in comp.dsp12 years ago 2 replies

Hi, I'm looking to port FFTW to be used under VisualDSP. Has anyone done this before? If so, is it possible to send me the ported FFTW code...

Hi, I'm looking to port FFTW to be used under VisualDSP. Has anyone done this before? If so, is it possible to send me the ported FFTW code at sbw@appsig.com? I found one post here: http://www.dsprelated.com/showmessage/35481/1.php I'm still trying to contact that person. Thank you!


[FFTW] Cyclic results with FFTW?

Started by Fred in comp.dsp13 years ago 4 replies

Dear all, I implemented some test FFT's from various libraries, having decomposed and reconstructed a simple signal (sine), my code...

Dear all, I implemented some test FFT's from various libraries, having decomposed and reconstructed a simple signal (sine), my code worked for all of them however, the signal I got using fftw was not reconstructed correctly, indeed, the transform is not cyclic. How to get cyclic output from fftw? Below is a code in 1D I used. sorry to ask such a trivial question and thanks for your ...


Scaling inverse result of FFT with FFTW

Started by Anonymous in comp.dsp11 years ago 2 replies

Hi, I have problems working with FFTW (www.fftw.org). I need to transform a 2-dimensional array into its fourier spectrum, modify some of...

Hi, I have problems working with FFTW (www.fftw.org). I need to transform a 2-dimensional array into its fourier spectrum, modify some of the coefficients and invert it back. It is part of a watermarking algorithm for images that works in the fourier spectrum. My code: const int IMG_SIZE = 1024; fftw_plan p; fftw_complex *in, *out, *out2; in = (fftw_complex*) fftw_malloc(sizeof(fftw...


Bandpass with FFTW

Started by pokey909 in comp.dsp12 years ago 2 replies

Hi! I am sampling at 256Hz and I want to filter out all frequencies except 1-9Hz. The filter should have the highest attenuation as possible....

Hi! I am sampling at 256Hz and I want to filter out all frequencies except 1-9Hz. The filter should have the highest attenuation as possible. My approach would be to use the FFTW library, transform from time to freq. domain and set all bins which are outside of my passband to 0 (like a rectangular window). But honestly I dont have a clue how to accomplish that with FFTW. I tried a hartley tran...


Multi-threaded FFTW

Started by Cristiano in comp.dsp10 years ago 3 replies

I'm using the FFTW library implemented as DLL under Win XP. Now I'm writing (in C++) a multi-threaded application which call the FFTW functions...

I'm using the FFTW library implemented as DLL under Win XP. Now I'm writing (in C++) a multi-threaded application which call the FFTW functions from two function in my code at the same time and, obviously, the application crashes. Is there any way to use the FFTW library in a multi-threaded application? Thanks Cristiano


FFTW Help

Started by Raeldor in comp.dsp7 years ago 8 replies

Hi All, I'm doing some tests with FFTW and it seems to be working ok, but I am seeing something that's a little odd and was wondering if my...

Hi All, I'm doing some tests with FFTW and it seems to be working ok, but I am seeing something that's a little odd and was wondering if my reasoning for it happening was correct. Basically, I have a 3 second 440hz sine wave file created in Audacity at 44.1khz sampling rate. I am running FFTW on a 4096 size window on the data and moving the window along by a small amount each time. I ...


fftw tuning

Started by Felipe G. Nievinski in comp.dsp7 years ago 3 replies

The documentation for Matlab's fftw interface states that: fftw('planner', method) sets the method by which the tuning algorithm searches...

The documentation for Matlab's fftw interface states that: fftw('planner', method) sets the method by which the tuning algorithm searches for a good FFT algorithm when the dimension of the FFT is _not_ a power of 2. So when the input dimension _is_ a power of 2 there is no potential speed up in tuning the FFTW library? I seem to be getting different performance for different tuning e...


FFTW and VB.NET

Started by vilaemail in comp.dsp8 years ago 5 replies

Hi, I don't know where to post this (since FFTW developers do not provide help with VB, and posting on MSDN for non-VB related question is...

Hi, I don't know where to post this (since FFTW developers do not provide help with VB, and posting on MSDN for non-VB related question is kinda dumb) so I decided to ask you guys. :) I really can't import FFTW library in VB.NET 9 (VS 2008). When trying to reference to it i get this error message: A reference to '...\libfftw3-3.dll' could not be added. Please make sure that the file is ac...


FFTW Fortran Real2Complex R2C output array structure? fftw_plan_dft_r2c_3d?

Started by Robert S. in comp.dsp10 years ago 2 replies

Hi, I'm using the FFTW package and am using the fortan wrappers to compute a 3D transform. This I seem to do successfully, however I can not...

Hi, I'm using the FFTW package and am using the fortan wrappers to compute a 3D transform. This I seem to do successfully, however I can not seem to disentangle the raw output. > From studying the figure on page 8 of the fftw 3.1.2 manual this is what I think is going on: For the output complex array I do the following shuffle: ------------------------------------------------- sub


FFTW Real FFT

Started by Anonymous in comp.dsp11 years ago 4 replies

Hello, simple question: I have a time series with lots of entries (more than int). How can I use FFTW to do a FFT? The problem is, that FFTW...

Hello, simple question: I have a time series with lots of entries (more than int). How can I use FFTW to do a FFT? The problem is, that FFTW can only handle up to "int n" entries in the datafile... Any idea? Thanks a lot! Mark