> On Jul 5, 2:23 am, Fatemeh gmail.com> wrote:
>
>
>

>> Dear all;

>

>> I'm going to use rlft3.f (3D Fast Fourier transform subroutine in
>> Numerical Recipes book )
>> I have constructed a 107*107*107 mesh for data.
>> I should call rlft3(data,speg,nn1,nn2,nn3,isign).
>> -----------------------------------------------------------------------------
>> SUBROUTINE rlft3(data,speq,nn1,nn2,nn3,isign)
>> INTEGER isign,nn1,nn2,nn3
>> COMPLEX data(nn1/2,nn2,nn3),speq(nn2,nn3)
>> -----------------------------------------------------------------------------
>> 1- I don't understand why for data is written nn1/2 ? I have a
>> 107*107*107 mesh!!!
>> 2- Is it true to put nn1=nn2=nn3=107
>> 3- I don't know what should I put instead of speq ? ...

> Get a real FFT routine somewhere!
> Numerical Recipes is great as a primer,
> but for the real work, use something real!

> Get a real FFT routine somewhere!
> Numerical Recipes is great as a primer,
> but for the real work, use something real!

> Arjan wrote:

>> Get a real FFT routine somewhere!
>> Numerical Recipes is great as a primer,
>> but for the real work, use something real!

>
> Do you know of a web site that compares the speed of various
> FFT routines? Or is there one FFT implementation that is
> generally regarded as the fastest? (I'm more interested in
> 2D FFT than in 3D.)