*DECK EZFFTI
SUBROUTINE EZFFTI (N, WSAVE)
C***BEGIN PROLOGUE EZFFTI
C***PURPOSE Initialize a work array for EZFFTF and EZFFTB.
C***LIBRARY SLATEC (FFTPACK)
C***CATEGORY J1A1
C***TYPE SINGLE PRECISION (EZFFTI-S)
C***KEYWORDS FFTPACK, FOURIER TRANSFORM
C***AUTHOR Swarztrauber, P. N., (NCAR)
C***DESCRIPTION
C
C Subroutine EZFFTI initializes the work array WSAVE which is used in
C both EZFFTF and EZFFTB. The prime factorization of N together with
C a tabulation of the trigonometric functions are computed and
C stored in WSAVE.
C
C Input Parameter
C
C N the length of the sequence to be transformed.
C
C Output Parameter
C
C WSAVE a work array which must be dimensioned at least 3*N+15.
C The same work array can be used for both EZFFTF and EZFFTB
C as long as N remains unchanged. Different WSAVE arrays
C are required for different values of N.
C
C***REFERENCES P. N. Swarztrauber, Vectorizing the FFTs, in Parallel
C Computations (G. Rodrigue, ed.), Academic Press,
C 1982, pp. 51-83.
C***ROUTINES CALLED EZFFT1
C***REVISION HISTORY (YYMMDD)
C 790601 DATE WRITTEN
C 830401 Modified to use SLATEC library source file format.
C 860115 Modified by Ron Boisvert to adhere to Fortran 77 by
C changing dummy array size declarations (1) to (*).
C 861211 REVISION DATE from Version 3.2
C 881128 Modified by Dick Valent to meet prologue standards.
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE EZFFTI
DIMENSION WSAVE(*)
C***FIRST EXECUTABLE STATEMENT EZFFTI
IF (N .EQ. 1) RETURN
CALL EZFFT1 (N,WSAVE(2*N+1),WSAVE(3*N+1))
RETURN
END