fft1dui(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;
         coeff = scfft1dui( 200, NULL);

SEE ALSO
          fft, scfft1du, dzfft1du