S-Lang GSL Module Reference: gslfft: The GSL FFT module

Next Previous Contents

## 7. gslfft: The GSL FFT module

The `gslfft` may be used to compute N dimensional fast fourier transforms (FFT). The module itself currently provides a single function called `_gsl_fft_complex` that performs a forward or backward n-dimensional FFT. The underlying GSL routines used by this function are the Swarztrauber mixed-radix routines from FFTPACK and the more general Singleton routine.

The `_gsl_fft_complex` function is not meant to be called directly; rather the user should call the `fft` function, which provides a convenient wrapper for the `_gsl_fft_complex` function.

## 7.1 Fast Fourier Transform Routines

### _gsl_fft_complex

Synopsis

  Perform an N-d FFT

Usage

  `y = _gsl_fft_complex (x, dir)`

Description

  This routine computes the FFT of an array `x` and returns the result. The integer-valued parameter `dir` parameter specifies the direction of the transform. A forward transform will be produced for positive values of `dir` and a reverse transform will be computed for negative values.

  The result will be a complex array of the same size and dimensionality as the the input array.

Notes

  It is better to call this routine indirectly using the `fft` function.

See Also

  `fft`

### fft

Synopsis

  Perform an N-d FFT

Usage

  `y = fft (x, dir)`

Description

  This routine computes the FFT of an array `x` and returns the result. The integer-valued parameter `dir` parameter specifies the direction of the transform. A forward transform will be produced for positive values of `dir` and a reverse transform will be computed for negative values.

  The result will be a complex array of the same size and dimensionality as the the input array.

Notes

  This routine is currently a wrapper for the `_gsl_fft_complex` function.

See Also

  `_gsl_fft_complex`

Next Previous Contents