mirror of
https://git.planet-casio.com/Lephenixnoir/OpenLibm.git
synced 2025-01-01 06:23:39 +01:00
89 lines
3 KiB
Fortran
89 lines
3 KiB
Fortran
*DECK PASSB3
|
|
SUBROUTINE PASSB3 (IDO, L1, CC, CH, WA1, WA2)
|
|
C***BEGIN PROLOGUE PASSB3
|
|
C***SUBSIDIARY
|
|
C***PURPOSE Calculate the fast Fourier transform of subvectors of
|
|
C length three.
|
|
C***LIBRARY SLATEC (FFTPACK)
|
|
C***TYPE SINGLE PRECISION (PASSB3-S)
|
|
C***AUTHOR Swarztrauber, P. N., (NCAR)
|
|
C***ROUTINES CALLED (NONE)
|
|
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 (a) changing dummy array size declarations (1) to (*),
|
|
C (b) changing definition of variable TAUI by using
|
|
C FORTRAN intrinsic function SQRT instead of a DATA
|
|
C statement.
|
|
C 881128 Modified by Dick Valent to meet prologue standards.
|
|
C 890831 Modified array declarations. (WRB)
|
|
C 891214 Prologue converted to Version 4.0 format. (BAB)
|
|
C 900402 Added TYPE section. (WRB)
|
|
C***END PROLOGUE PASSB3
|
|
DIMENSION CC(IDO,3,*), CH(IDO,L1,3), WA1(*), WA2(*)
|
|
C***FIRST EXECUTABLE STATEMENT PASSB3
|
|
TAUR = -.5
|
|
TAUI = .5*SQRT(3.)
|
|
IF (IDO .NE. 2) GO TO 102
|
|
DO 101 K=1,L1
|
|
TR2 = CC(1,2,K)+CC(1,3,K)
|
|
CR2 = CC(1,1,K)+TAUR*TR2
|
|
CH(1,K,1) = CC(1,1,K)+TR2
|
|
TI2 = CC(2,2,K)+CC(2,3,K)
|
|
CI2 = CC(2,1,K)+TAUR*TI2
|
|
CH(2,K,1) = CC(2,1,K)+TI2
|
|
CR3 = TAUI*(CC(1,2,K)-CC(1,3,K))
|
|
CI3 = TAUI*(CC(2,2,K)-CC(2,3,K))
|
|
CH(1,K,2) = CR2-CI3
|
|
CH(1,K,3) = CR2+CI3
|
|
CH(2,K,2) = CI2+CR3
|
|
CH(2,K,3) = CI2-CR3
|
|
101 CONTINUE
|
|
RETURN
|
|
102 IF(IDO/2.LT.L1) GO TO 105
|
|
DO 104 K=1,L1
|
|
CDIR$ IVDEP
|
|
DO 103 I=2,IDO,2
|
|
TR2 = CC(I-1,2,K)+CC(I-1,3,K)
|
|
CR2 = CC(I-1,1,K)+TAUR*TR2
|
|
CH(I-1,K,1) = CC(I-1,1,K)+TR2
|
|
TI2 = CC(I,2,K)+CC(I,3,K)
|
|
CI2 = CC(I,1,K)+TAUR*TI2
|
|
CH(I,K,1) = CC(I,1,K)+TI2
|
|
CR3 = TAUI*(CC(I-1,2,K)-CC(I-1,3,K))
|
|
CI3 = TAUI*(CC(I,2,K)-CC(I,3,K))
|
|
DR2 = CR2-CI3
|
|
DR3 = CR2+CI3
|
|
DI2 = CI2+CR3
|
|
DI3 = CI2-CR3
|
|
CH(I,K,2) = WA1(I-1)*DI2+WA1(I)*DR2
|
|
CH(I-1,K,2) = WA1(I-1)*DR2-WA1(I)*DI2
|
|
CH(I,K,3) = WA2(I-1)*DI3+WA2(I)*DR3
|
|
CH(I-1,K,3) = WA2(I-1)*DR3-WA2(I)*DI3
|
|
103 CONTINUE
|
|
104 CONTINUE
|
|
RETURN
|
|
105 DO 107 I=2,IDO,2
|
|
CDIR$ IVDEP
|
|
DO 106 K=1,L1
|
|
TR2 = CC(I-1,2,K)+CC(I-1,3,K)
|
|
CR2 = CC(I-1,1,K)+TAUR*TR2
|
|
CH(I-1,K,1) = CC(I-1,1,K)+TR2
|
|
TI2 = CC(I,2,K)+CC(I,3,K)
|
|
CI2 = CC(I,1,K)+TAUR*TI2
|
|
CH(I,K,1) = CC(I,1,K)+TI2
|
|
CR3 = TAUI*(CC(I-1,2,K)-CC(I-1,3,K))
|
|
CI3 = TAUI*(CC(I,2,K)-CC(I,3,K))
|
|
DR2 = CR2-CI3
|
|
DR3 = CR2+CI3
|
|
DI2 = CI2+CR3
|
|
DI3 = CI2-CR3
|
|
CH(I,K,2) = WA1(I-1)*DI2+WA1(I)*DR2
|
|
CH(I-1,K,2) = WA1(I-1)*DR2-WA1(I)*DI2
|
|
CH(I,K,3) = WA2(I-1)*DI3+WA2(I)*DR3
|
|
CH(I-1,K,3) = WA2(I-1)*DR3-WA2(I)*DI3
|
|
106 CONTINUE
|
|
107 CONTINUE
|
|
RETURN
|
|
END
|