NAME

dfft3f - compute the Fourier coefficients of a real periodic sequence.  The xFFT operations are unnormalized, so a call of xFFT3F followed by a call of xFFT3B will multiply the input sequence by M∗N∗K. 

SYNOPSIS

SUBROUTINE RFFT3F (PLACE, FULL, M, N, K, SX, LDX, SY, LDY, RWSAVE, LWSAVE)

SUBROUTINE DFFT3F (PLACE, FULL, M, N, K, DX, LDX, DY, LDY, DWSAVE, LWSAVE)

#include <sunperf.h>

void rfft3f (char place, char full, int m, int n, int k, float ∗sx, int ldx, float ∗sy, int ldy, float ∗wsave, int lwsave) ;

void dfft3f (char place, char full, int m, int n, int k, double ∗dx, int ldx, double ∗dy, int ldy, double ∗wsave, int lwsave) ;

ARGUMENTS

PLACE Select an in-place (’I’ or ’i’) or out-of-place (’O’ or ’o’) transform. 

FULL Select a full (’F’ or ’f’) or partial (’ ’) representation of the results.  If the caller selects full representation then an MxNxK real array will transform to produce an MxNxK complex array.  If the caller does not select full representation then an MxNxK real array will transform to a (M/2+1)xNxK complex array that takes advantage of the symmetry properties of a transformed real sequence. 

M Number of rows to be transformed.  These subroutines are most efficient when M is a product of small primes.  M >= 0. 

N Number of columns to be transformed.  These subroutines are most efficient when N is a product of small primes.  N >= 0. 

K Number of planes to be transformed.  These subroutines are most efficient when K is a product of small primes.  K >= 0. 

xX On entry, a three-dimensional array xX(LDX,N,K) that contains the sequences to be transformed.  On exit, the transformed sequences if the caller selected an in-place transform. 

LDX Leading dimension of the array containing the data to be transformed.  LDX >= M. 

xY On exit, xY(LDY,N,K) contains the transformed sequences if the caller selected an out of place transform.  If the caller selected an in-place transform then this argument is never referenced. 

LDY Leading dimension of the array for an out-of-place transform.  LDY >= M. 

xWSAVE On entry, an array with dimension of at least (M + N + MAX(M,N,K) + 45).  The array must have been initialized by xFFT3I. 

LWSAVE Length of the xWSAVE array. 

SunOS 5.0  —  Last change: 10 Dec 1998