EZFFTI(3)

SYNOPSIS
SUBROUTINE EZFFTI (N, WSAVE)

NAME
ezffti - Initialize a work array for EZFFTF and EZFFTB.

LIBRARY
SLATEC (FFTPACK)

CATEGORY
J1A1

TYPE
SINGLE PRECISION (EZFFTI-S)

KEYWORDS
FFTPACK, FOURIER TRANSFORM

AUTHOR
Swarztrauber, P. N., (NCAR)

DESCRIPTION
Subroutine EZFFTI initializes the work array WSAVE which is used in both EZFFTF and EZFFTB. 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. Output Parameter WSAVE a work array which must be dimensioned at least 3*N+15. The same work array can be used for both EZFFTF and EZFFTB as long as N remains unchanged. Different WSAVE arrays are required for different values of N.

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

ROUTINES CALLED
EZFFT1

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)