FFT Lib?

[Fawzi Mohamed]

On 28-lug-10, at 06:22, Don wrote:

> dsimcha wrote:
>> I'm going to need an FFT library to perform some convolutions at  
>> some point
>> soon.  Two absolute, non-negotiable requirements are that it be  
>> written in
>> pure D and that it be Boost or compatibly (i.e. zlib or public  
>> domain)
>> licensed.  I also prefer "simple and good enough"
>
> What does "simple" mean?
> If you're happy with lengths being restricted to powers of 2, it's  
> simple. Most of the complexity of something like FFTW comes from  
> support for arbitrary lengths.

and cache awarness..., but yes efficiently supporting arbitrary  
lengths is difficult.

>> 3.  If I do end up writing my own or porting, is there sufficient  
>> interest in
>> this that I should try to target it for std.numerics, or would I be  
>> better off
>> just making it good enough for my use case?
>
> I think that a basic power-of-2 FFT is simple enough, and  
> sufficiently widely used to be worth including.

Note that the fft from fftpack support arbitrary lengths (the  
efficiency decreases, but not so drastically).
I would put something like that for "casual" use, so that one doesn't  
have to worry too much about sizes.
If he needs something better then he should start to worry about it.  
For example one could have a routine returning the next "good" size,  
always increasing.

Fawzi