fftw

I am trying fftw with c++. I want to test that it works correct. I implemented a simple ifft(fft(shift(data)) - data == 0 test, that fails completely. The testdata is a rect function, with amplitude and phase 1. The matlab code for comparison works perfectly with the same test. The basic question is: what am I doing wrong? Here the matlab code (which is also using fftw...) FFTW dll/.h is latest. data = zeros(1, 64); halfsize = numel(data)/2; data(halfsize-10:halfsize+10) = 1; phase = ones(size(data)); data = data.*exp(phase*sqrt(-1)); Ft = fft(fftshift(data)); In C++ the code is (not complete)

I have installed fftw C library succefully on my linux system. Here is more info about fftw c => http://www.fftw.org/ I have a sample C code which can call fftw C functions successfully. Below is a C ccode and command to run the C code: Code: #include <stdio.h> #include <stdlib.h> #include <stdint.h> #include <math.h> #include <fftw3.h> int main(void) { double FFT_in[] = {0.1, 0.6, 0.1, 0.4, 0.5, 0, 0.8, 0.7, 0.8, 0.6, 0.1,0}; double *IFFT_out; int i,size = 12; fftw_complex *middle; fftw_plan fft; fftw_plan ifft; middle = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*size); IFFT_out =

I have an AudioRecord thread that writes to database. Now I want to use some audio data in buffer at some intervals and process it using FFT . I want to send audio buffer to FFT as parameter. When I am trying to use a common buffer then its giving me libc error. How can I use a common buffer to pass it to FFT and also write it to a storage? When I tried using different read calls there was situation of data loss and hence cant use that. Following is my code public void start() { startRecording(); _isRecording = true; _recordingThread = new Thread(new Runnable() { public void run() {

recently I faced some problems concerning the use of fftw and it's c2c transformation (see: 3d c2c fft with fftw library ). As I located my problems in the use of the fftw lib I created a new Question in order to discus this situation in a more concrete way. Since I am doing a complex to complex transform with real data my transformed data in fourier space is supposed to be symmetric: F[n] = con(F[N-n]) Now I did some transformations with small blocks of test-data to check the transformed data for this symmetry. For 1D transform at every things worked as expected, but for higher dimensions I

I have a question about the Microsoft PPL library, and parallel programming in general. I am using FFTW to perform a large set (100,000) of 64 x 64 x 64 FFTs and inverse FFTs. In my current implementation, I use a parallel for loop and allocate the storage arrays within the loop. I have noticed that my CPU usage only tops out at about 60-70% in these cases. (Note this is still better utilization than the built in threaded FFTs provided by FFTW which I have tested). Since I am using fftw_malloc, is it possible that excessive locking is occurring which is preventing full usage? In light of this,

I am currently writing a genre classification application as my final year project in Computer Engineering. I initially wrote the feature extraction code (implementing FFTW) in C and now I need to implement it on Android via the NDK. This is my first NDK project so I'm still getting the hang of things but I have compiled the FFTW3 library for Android according to this guide . I didn't do the very last step because I didn't think it was right for what I need. My question is how do I, after the compile step, use the library in the main NDK application that calls on it? Do I everything normally

I'm trying to do some filtering with FFT. I'm using r2r_1d plan and I have no idea how to do the inverse transform... void PerformFiltering(double* data, int n) { /* FFT */ double* spectrum = new double[n]; fftw_plan plan; plan = fftw_plan_r2r_1d(n, data, spectrum, FFTW_REDFT00, FFTW_ESTIMATE); fftw_execute(plan); // signal to spectrum fftw_destroy_plan(plan); /* some filtering here */ /* Inverse FFT */ plan = fftw_plan_r2r_1d(n, spectrum, data, FFTW_REDFT00, FFTW_ESTIMATE); fftw_execute(plan); // spectrum to signal (inverse FFT) fftw_destroy_plan(plan); } Am I doing all the things right? I'm