Thanks AlexTP, I have renamed everything and retired my CX function.
MarkMLI
I suppose the vast number of external pascal pre written units would cover many of the dll exports.
I know about ucomplex now, and I like it.
The problem with the DLL export is that it's very much Windows- (hence also Intel/AMD-) specific... in fact is probably tied fairly tightly to a small range of versions. So /particularly/ since you've already put effort into the translation, if you see anything notable it's worth commenting.
Just in case: note that there's an FFTW interface with FPC, although when I last looked some target combinations lacked the prerequisite library so I ended up (also) transcribing a simple alternative implementation.
MarkMLl