"Fast Fourier Transform of a Step-function in 3-dimonsional" please help me.

[Tobias Burnus]

fatemeh.mirjani wrote:
> I need a subroutine of Fortran90 about "Fast Fourier Transform of a Step-function in 3-dimonsional."
> I read the related subroutines in Numerical Recipes Book, but I couldn't match it for a 3D step function.
> Whould you please let me to have access to a subroutine for mentioned goal?
>   
I use for FFT always the FFTW library (http://www.fftw.org/), which is 
written in C but can easily be accessed from Fortran.

See:
http://www.fftw.org/fftw3_doc/Calling-FFTW-from-Fortran.html
http://www.fftw.org/fftw3_doc/Multi_002dDimensional-DFTs-of-Real-Data.html

Otherwise: The is a bit off topic. The mailing list is for GNU Fortran 
(gfortran) questions. For general Fortran questions I'd suggest to ask 
in the comp.lang.fortran newsgroup, which can be also accessed via 
http://groups.google.com/group/comp.lang.fortran/

Tobias