spffte.f File Reference

Perform multiple fast Fourier transforms. More...

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Functions/Subroutines
subroutine	spffte (IMAX, INCW, INCG, KMAX, W, G, IDIR, AFFT)
	This subprogram performs multiple fast Fourier transforms between complex amplitudes in Fourier space and real values in cyclic physical space. More...

Detailed Description

Perform multiple fast Fourier transforms.

Program History Log

Date	Programmer	Comments
1998-12-18	Iredell	Initial.
2012-11-12	Mirvis	fixing hard-wired types problem on Intel/Linux.

Author

Iredell

Date

96-02-20

Definition in file spffte.f.

Function/Subroutine Documentation

spffte()

subroutine spffte	(	integer, intent(in)	IMAX,
		integer, intent(in)	INCW,
		integer, intent(in)	INCG,
		integer, intent(in)	KMAX,
		real, dimension(2*incw,kmax), intent(inout)	W,
		real, dimension(incg,kmax), intent(inout)	G,
		integer, intent(in)	IDIR,
		real(8), dimension(50000+4*imax), intent(inout)	AFFT
	)

This subprogram performs multiple fast Fourier transforms between complex amplitudes in Fourier space and real values in cyclic physical space.

This subprogram must be invoked first with IDIR=0 to initialize trigonemetric data. Use subprogram spfft1() to perform an FFT without previous initialization.

This version invokes the IBM ESSL FFT.

Note

The restrictions on IMAX are that it must be a multiple of 1 to 25 factors of two, up to 2 factors of three, and up to 1 factor of five, seven and eleven.

If IDIR=0, then W and G need not contain any valid data. The other parameters must be supplied and cannot change in succeeding calls until the next time it is called with IDIR=0.

This subprogram is thread-safe.

Parameters

	IMAX	number of values in the cyclic physical space (see limitations on imax in remarks below.)
	INCW	first dimension of the complex amplitude array (INCW >= IMAX/2+1)
	INCG	first dimension of the real value array (INCG >= IMAX)
	KMAX	number of transforms to perform
[out]	W	complex amplitudes if IDIR>0
[out]	G	real values if IDIR<0
	IDIR	direction flag IDIR=0 to initialize trigonometric data IDIR>0 to transform from Fourier to physical space IDIR<0 to transform from physical to Fourier space
[out]	AFFT	auxiliary array if IDIR<>0

Author

Iredell

Date

96-02-20

Definition at line 48 of file spffte.f.

References dcrft(), drcft(), scrft(), and srcft().

Referenced by sptranf0(), and sptranf1().