fft_macros.m4h

This one is quite a pain, especially since it uses m4. The standard quotation characters `' have been replaced by []. The file fourier_transform.fp gets preprocessed into fourier_transform.p.f. To check correctness of the macros, look at fourier_transform.p.f Look up the man on the fourier transforms (e.g man fft), add new macros accordingly to fft_macros.m4h.

Don't forget to provide for workspace in fft_workspace.fp, and for a list of acceptable FFT lengths in adjust_fft.fp. Once you have that done, you are through the worst. Have a look at fourier_transform.fp. If the fourier transform interfaces are awkward, you might have to make some changes there as well. Make use of optimized routines to perform the convolution, rather than using the vanilla loop. Try if the preprocessor option FAST_CONVOLUTE results in any speedup - it usually does for machines where no multiple-FFT routines are available.

At some point, the code was running also on cray vector machines. This is no longer the case, although still all the code is there, and it should not be too much work to get it going again.