*DECK CFFTI
SUBROUTINE CFFTI (N, WSAVE)
C***BEGIN PROLOGUE CFFTI
C***SUBSIDIARY
C***PURPOSE Initialize a work array for CFFTF and CFFTB.
C***LIBRARY SLATEC (FFTPACK)
C***CATEGORY J1A2
C***TYPE COMPLEX (RFFTI-S, CFFTI-C)
C***KEYWORDS FFTPACK, FOURIER TRANSFORM
C***AUTHOR Swarztrauber, P. N., (NCAR)
C***DESCRIPTION
C
C ********************************************************************
C * NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE *
C ********************************************************************
C * *
C * This routine uses non-standard Fortran 77 constructs and will *
C * be removed from the library at a future date. You are *
C * requested to use CFFTI1. *
C * *
C ********************************************************************
C
C Subroutine CFFTI initializes the array WSAVE which is used in
C both CFFTF and CFFTB. 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 4*N+15.
C The same work array can be used for both CFFTF and CFFTB
C as long as N remains unchanged. Different WSAVE arrays
C are required for different values of N. The contents of
C WSAVE must not be changed between calls of CFFTF or CFFTB.
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 CFFTI1
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 900131 Routine changed from user-callable to subsidiary
C because of non-standard Fortran 77 arguments in the
C call to CFFTB1. (WRB)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE CFFTI
DIMENSION WSAVE(*)
C***FIRST EXECUTABLE STATEMENT CFFTI
IF (N .EQ. 1) RETURN
IW1 = N+N+1
IW2 = IW1+N+N
CALL CFFTI1 (N,WSAVE(IW1),WSAVE(IW2))
RETURN
END