SINQI(3)

SYNOPSIS
SUBROUTINE SINQI (N, WSAVE)

NAME
sinqi - Initialize a work array for SINQF and SINQB.

LIBRARY
SLATEC (FFTPACK)

CATEGORY
J1A3

TYPE
SINGLE PRECISION (SINQI-S)

KEYWORDS
FFTPACK, FOURIER TRANSFORM

AUTHOR
Swarztrauber, P. N., (NCAR)

DESCRIPTION
Subroutine SINQI initializes the array WSAVE which is used in both SINQF and SINQB. The prime factorization of N together with a tabulation of the trigonometric functions are computed and stored in WSAVE. Input Parameter N the length of the sequence to be transformed. The method is most efficient when N is a product of small primes. Output Parameter WSAVE a work array which must be dimensioned at least 3*N+15. The same work array can be used for both SINQF and SINQB as long as N remains unchanged. Different WSAVE arrays are required for different values of N. The contents of WSAVE must not be changed between calls of SINQF or SINQB.

REFERENCES
P. N. Swarztrauber, Vectorizing the FFTs, in Parallel Computations (G. Rodrigue, ed.), Academic Press, 1982, pp. 51-83.

ROUTINES CALLED
COSQI

REVISION HISTORY (YYMMDD)
790601 DATE WRITTEN
830401 Modified to use SLATEC library source file format.
860115 Modified by Ron Boisvert to adhere to Fortran 77 by changing dummy array size declarations (1) to (*)
861211 REVISION DATE from Version 3.2
881128 Modified by Dick Valent to meet prologue standards.
891214 Prologue converted to Version 4.0 format. (BAB)
920501 Reformatted the REFERENCES section. (WRB)