sfft3du,dfft3du(3F) sfft3du,dfft3du(3F)NAME
dfft3du, sfft3du - 3D Real to Complex Fast Fourier Transform.
FORTRAN SPECIFICATION
subroutine DFFT3DU( job, n1, n2, n3, sequence, ld1, ld2, workspace )
integer job, n1, n2, n3, ld1, ld2
double precision sequence(ld1,ld2,*), workspace(*)
subroutine SFFT3DU( job, n1, n2, n3, sequence, ld1, ld2, workspace )
integer job, n1, n2, n3, ld1, ld2
real sequence(ld1,ld2,*), workspace(*)
C SPECIFICATION
int dfft3du( int job, int n1, int n2, int n3,
double *sequence, int ld1, int ld2,
double *workspace)
int sfft3du( int job, int n1, int n2, int n3,
float *sequence, int ld1, int ld2,
float *workspace)
DESCRIPTION
DFFT3DU and SFFT3DU compute the 3 dimensional complex Fourier transform
of a real periodic sequence.
NOTE: These routines are provided only for compatibility with previous
releases of complib.
PARAMETERS
JOB - INTEGER
On entry specifies whether to perform a forward or backward Fast Fourier
Transform:
JOB = -1, forward FFT
JOB = 1, backward FFT Unchanged on exit.
N1 - INTEGER.
On entry, N1 specifies the number of elements in the first dimension of
the sequence. Unchanged on exit.
N2 - INTEGER.
On entry, N2 specifies the number of elements in the second dimension of
the sequence. Unchanged on exit.
N3 - INTEGER.
On entry, N3 specifies the number of elements in the third dimension of
the sequence. Unchanged on exit.
SEQUENCE - Array.
Array of DIMENSION ( LD1, LD2, n3 ). Array containing the (ld1*ld2*n3)
elements for the FFT. On exit, SEQUENCE is overwritten by the 3D
transform.
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sfft3du,dfft3du(3F) sfft3du,dfft3du(3F)
LD1 - INTEGER.
On entry, LD1 specifies the first dimension of the array SEQUENCE as
declared in the calling (sub)program. LD1 must be at least max( 1,
2*((n1+2)/2) ). Unchanged on exit.
LD2 - INTEGER.
On entry, LD2 specifies the second dimension of the array SEQUENCE as
declared in the calling (sub)program. LD2 must be at least max( 1, n2 ).
Unchanged on exit.
WORKSPACE - Array.
Array of dimension at least (N1+15) + 2*(N2+15) + 2*(N3+15). Array
containing the Sines/Cosines and factorization of N1, N2 and N3.
WORKSPACE needs to be initialized by a call to sfft3dui or dfft3dui.
SEE ALSO
o32fft
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