"Fast Fourier Transform of a step-function in 3-dimonsional"

[fatemeh.mirjani]

Dear all;

I need a subroutine in Fortran90 for "Fast Fourier Transform of a step-function in 3-dimonsional" . Would you please help me?
(because I'm a novitiate in Fortran90 programming.)

Any help is appreciated.

Best Regard,
Fatemeh

+------------------------------------------------------------------------------+
|Fatemeh Mirjani                              | Email: f_mirjani@ph.iut.ac.ir  |
|Computational Condensed Matter Research Lab. | Tel/Fax Office: +98311-3913746 |
|ICTP Affiliated Center in Isfahan,           | Tel Lab.: +98311-3913731       |
+----------Physics Department, Isfahan University of Technology, Iran----------+