# Difference between revisions of "How to use FFTW"

From Qt Wiki

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// A short tutorial: | // A short tutorial: | ||

− | // http://www2.math.uu.se/~figueras/ | + | // http://www2.math.uu.se/~figueras/Other/text/fftw_tutorial.pdf |

</code> | </code> |

## Latest revision as of 07:58, 10 March 2017

## Getting Started

**Note that this is done on an Ubuntu operating system, on Windows some steps are different.**

**Step 1**: Download FFTW from http://www.fftw.org/download.html

**Step 2**: Extract and Configure it (my path: /home/jafarabadi/Documents/fftw-3.3.4)

cd /home/jafarabadi/Documents/fftw-3.3.4 ./configure make make install

- Alternatively install fftw through your package manager (e.g. pacman -Sy fftw)

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

LIBS += -lfftw3

**Step 4**: Example

```
```

- include <fftw3.h>

int N;

// Set N to the number of complex elements in the input array

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

// Initialize 'in' with N complex entries

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

// Use 'out' for something

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

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