*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