View source for How to use FFTW

[[Category:Learning::HowTo]]

= 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 ([[http://www.fftw.org/download.html]])

* Step2: Extract and Configure it (my path: /home/jafarabadi/Documents/fftw-3.3.4)
<code>cd /home/jafarabadi/Documents/fftw-3.3.4
chmod ''x configure
./configure
make
make install</code>

* Step 3: Add library to project: first open [your_project_name].pro file in Qt Creator and add this line:
<code>LIBS''= -lfftw3<code>

* Step 4: Example
</code>#include <fftw3.h></code>
<code>int N;

fftw_complex *in, '''out;
in = (fftw_complex''') fftw_malloc(sizeof(fftw_complex)'''N);
out = (fftw_complex''') fftw_malloc(sizeof(fftw_complex)*N);

fftw_plan my_plan;
my_plan = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(my_plan);

fftw_destroy_plan(my_plan);
fftw_free(in);
fftw_free(out);

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