Tech Tip: Fast Fourier Transforms (FFTs)

If your code makes calls to vendor performance library FFT routines then these calls could be replaced by calls to the corresponding NAG SMP Library (C06 Chapter) routines. The NAG routines will call the vendor FFT routines whenever possible so that performance is not lost. This change of calls makes the code more portable by removing the reliance on the vendor FFT routines. Now when porting to a different platform and linking with the appropriate NAG SMP Library, the calls to the NAG FFT routines will automatically pick up the vendor FFT routines for that platform whenever possible.

When performing multiple 1-dimensional FFTs, the sequences to be transformed are best stored as columns of a 2-dimensional array (i.e. the elements of each sequence should be stored contiguously).

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