mirror of
https://git.planet-casio.com/Lephenixnoir/OpenLibm.git
synced 2025-01-01 06:23:39 +01:00
62 lines
2.6 KiB
Fortran
62 lines
2.6 KiB
Fortran
*DECK RFFTI
|
|
SUBROUTINE RFFTI (N, WSAVE)
|
|
C***BEGIN PROLOGUE RFFTI
|
|
C***SUBSIDIARY
|
|
C***PURPOSE Initialize a work array for RFFTF and RFFTB.
|
|
C***LIBRARY SLATEC (FFTPACK)
|
|
C***CATEGORY J1A1
|
|
C***TYPE SINGLE PRECISION (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 RFFTI1. *
|
|
C * *
|
|
C ********************************************************************
|
|
C
|
|
C Subroutine RFFTI initializes the array WSAVE which is used in
|
|
C both RFFTF and RFFTB. The prime factorization of N together with
|
|
C a tabulation of the trigonometric functions are computed and
|
|
C stored in WSAVE.
|
|
C
|
|
C Input Argument
|
|
C
|
|
C N the length of the sequence to be transformed.
|
|
C
|
|
C Output Argument
|
|
C
|
|
C WSAVE a work array which must be dimensioned at least 2*N+15.
|
|
C The same work array can be used for both RFFTF and RFFTB
|
|
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 RFFTF or RFFTB.
|
|
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 RFFTI1
|
|
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 RFFTI
|
|
DIMENSION WSAVE(*)
|
|
C***FIRST EXECUTABLE STATEMENT RFFTI
|
|
IF (N .EQ. 1) RETURN
|
|
CALL RFFTI1 (N,WSAVE(N+1),WSAVE(2*N+1))
|
|
RETURN
|
|
END
|