How to use FFTW

How to compute FFT using FFTW in Qt

Getting Start

Note that I do this in Ubuntu operating system, in Windows some steps are different.

• Step1: Download FFTW ([[1]])

• Step2: Extract and Configure it (my path: /home/jafarabadi/Documents/fftw-3.3.4)
  

  cd /home/jafarabadi/Documents/fftw-3.3.4<br />chmod ''x configure<br />./configure<br />make<br />make install
  

* Step 3: Add library to project: first open [your_project_name].pro file in Qt Creator and add this line:

LIBS''= -lfftw3<code>

* Step 4: Example<br />

#include <fftw3.h&gt;

int N;

fftw_complex *in, '''out;<br />in = (fftw_complex''') fftw_malloc(sizeof(fftw_complex)'''N);<br />out = (fftw_complex''') fftw_malloc(sizeof(fftw_complex)*N);

fftw_plan my_plan;<br />my_plan = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_ESTIMATE);<br />fftw_execute(my_plan);

fftw_destroy_plan(my_plan);<br />fftw_free(in);<br />fftw_free(out);

// A short tutorial: http://www2.math.uu.se/~figueras/fftw_tutorial/text/fftw_tutorial.pdf