sfft1du,dfft1du(3F) sfft1du,dfft1du(3F)NAME
dfft1du, sfft1du - 1D Real to Complex Fast Fourier Transform.
FORTRAN SPECIFICATION
subroutine DFFT1DU( job, n, sequence, inc, workspace )
integer job, n, inc
double precision sequence(*), workspace(*)
subroutine SFFT1DU( job, n, sequence, inc, workspace )
integer job, n, inc
real sequence(*), workspace(*)
C SPECIFICATION
int sfft1du ( int job, int n, float *sequence,
int inc, float *workspace);
int dfft1du ( int job, int n, double *sequence,
int inc, double *workspace);
DESCRIPTION
DFFT1DU and SFFT1DU compute the 1 dimensional 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.
N - INTEGER.
On entry, N specifies the number of elements in the 1D FFT. Unchanged on
exit.
SEQUENCE - Array.
Array of dimension at least 2*( (N+2)/2 ). On entry it contains the
elements for the FFT. On exit, SEQUENCE is overwritten by the 1D
transform.
INC - INTEGER.
Increment between two consecutive elements of the sequence. Unchanged on
exit.
WORKSPACE - Array.
Array of dimension at least N + 15. On entry it contains the
Sines/Cosines and factorization of N. WORKSPACE needs to be initialized
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sfft1du,dfft1du(3F) sfft1du,dfft1du(3F)
by a call to sfft1dui or dfft1dui.
SEE ALSO
o32fft
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