vrfftb
vrfftb - compute a periodic sequence from its Fourier coefficients. The VRFFT operations are normalized, so a call of VRFFTF followed by a call of
VRFFTB will return the original sequence.
SUBROUTINE VRFFTB( M, N, X, XT, MDIMX, WSAVE)
INTEGER M, N, MDIMX
REAL X(MDIMX,*), XT(MDIMX,*), WSAVE(*)
SUBROUTINE VRFFTB_64( M, N, X, XT, MDIMX, WSAVE)
INTEGER*8 M, N, MDIMX
REAL X(MDIMX,*), XT(MDIMX,*), WSAVE(*)
SUBROUTINE FFTB( [M], [N], X, XT, [MDIMX], WSAVE)
INTEGER :: M, N, MDIMX
REAL, DIMENSION(:) :: WSAVE
REAL, DIMENSION(:,:) :: X, XT
SUBROUTINE FFTB_64( [M], [N], X, XT, [MDIMX], WSAVE)
INTEGER(8) :: M, N, MDIMX
REAL, DIMENSION(:) :: WSAVE
REAL, DIMENSION(:,:) :: X, XT
#include <sunperf.h>
void vrfftb(int m, int n, float *x, float *xt, int mdimx, float *wsave);
void vrfftb_64(long m, long n, float *x, float *xt, long mdimx, float *wsave);
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* M (input)
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The number of sequences to be transformed. M >= 0.
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* N (input)
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Length of the sequence to be transformed. These subroutines are
most efficient when N is a product of small primes. N >= 0.
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* X (input)
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On entry, an array of length N containing the sequence to be
transformed. For VRFFTF, a real two-dimensional array X(M,N) whose rows
contain the sequences to be transformed.
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* XT (input)
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A real two-dimensional work array with dimensions of (MDIMX x N).
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* MDIMX (input)
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Leading dimension of the arrays X and XT as specified in a dimension or type statement.
MDIMX >= M.
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* WSAVE (input)
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On entry, an array of dimension (N+15) or greater initialized by VRFFTI.