scfft1dui,dzfft1dui(3F) scfft1dui,dzfft1dui(3F)NAME
scfft1dui, dzfft1dui - initialize the coefficient array for real-to-
complex 1D FFT modules.
SYNOPSYS
FORTRAN SPECIFICATION
subroutine SCFFT1DUI( n, coeff )
integer n
real coeff(n+15)
subroutine DZFFT1DUI( n, coeff )
integer n
real*8 coeff(n+15)
C SPECIFICATION
#include <fft.h>
float *scfft1dui( int n, float *coeff);
double *dzfft1dui( int n, double *coeff);
DESCRIPTION
Initialize, the coefficient array which is used in the FFT modules. This
array contains the different twiddle factors and the factorization of N
into prime numbers.
As the FFT modules scfft1d or dzfft1d only read the coeff array, it may
be reused as long as necessary once it has been initialized.
In C, if ptr is NULL, scfft1dui or dzfft1dui returns a pointer to an
allocated buffer.
SCFFT1DUI should be used to initialize the coefficient array before any
call to SCFFT1DU
DZFFT1DUI should be used to initialize the coefficient array before any
call to DZFFT1DU
PARAMETERS
N - Integer. Specifies the length of the sequence to be transformed.
Unchanged on exit.
COEFF - Array (C or Fortran) or NULL pointer(C).
Example of Calling Sequence
Initializing a coefficient array for real-to-complex FFTs of size 200.
Fortran :
float coeff(200+15)
call scfft1dui( 200, coeff)
C :
#include <fft.h>
float *coeff;
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scfft1dui,dzfft1dui(3F) scfft1dui,dzfft1dui(3F)
coeff = scfft1dui( 200, NULL);
SEE ALSO
fft, scfft1du, dzfft1du
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