spfft1.f File Reference

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Functions/Subroutines
subroutine	spfft1 (IMAX, INCW, INCG, KMAX, W, G, IDIR)
	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

Author

IREDELL

Date

96-02-20

Definition in file spfft1.f.

Function/Subroutine Documentation

spfft1()

subroutine spfft1	(	integer, intent(in)	IMAX,
		integer, intent(in)	INCW,
		integer, intent(in)	INCG,
		integer, intent(in)	KMAX,
		complex, dimension(incw,kmax), intent(inout)	W,
		real, dimension(incg,kmax), intent(inout)	G,
		integer, intent(in)	IDIR
	)

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

Subprogram SPFFT1 initializes trigonometric data each call. Use subprogram SPFFT to save time and initialize once. this version invokes the ibm essl fft.

Parameters

	IMAX	- INTEGER NUMBER OF VALUES IN THE CYCLIC> PHYSICAL SPACE (SEE LIMITATIONS ON IMAX IN REMARKS BELOW.)
	INCW	- INTEGER FIRST DIMENSION OF THE COMPLEX AMPLITUDE ARRAY (INCW >= IMAX/2+1)
	INCG	- INTEGER FIRST DIMENSION OF THE REAL VALUE ARRAY (INCG >= IMAX)
	KMAX	- INTEGER NUMBER OF TRANSFORMS TO PERFORM
[out]	W	- COMPLEX(INCW,KMAX) COMPLEX AMPLITUDES IF IDIR>0
[out]	G	- REAL(INCG,KMAX) REAL VALUES IF IDIR<0
	IDIR	- INTEGER DIRECTION FLAG IDIR>0 TO TRANSFORM FROM FOURIER TO PHYSICAL SPACE IDIR<0 TO TRANSFORM FROM PHYSICAL TO FOURIER SPACE

SUBPROGRAMS CALLED:

• SCRFT IBM ESSL COMPLEX TO REAL FOURIER TRANSFORM
• SRCFT IBM ESSL REAL TO COMPLEX FOURIER TRANSFORM

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.

This subprogram is thread-safe.

Definition at line 36 of file spfft1.f.