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Viewing changes to Lib/Slatec/slatec/radf3.f

  • Committer: Bazaar Package Importer
  • Author(s): Ben Gertzfield
  • Date: 2002-04-08 18:47:16 UTC
  • Revision ID: james.westby@ubuntu.com-20020408184716-0hf64dc96kin3htp
Tags: upstream-2.3.2
Import upstream version 2.3.2

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Lib/Slatec/slatec/radf3.f
 
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*DECK RADF3
 
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      SUBROUTINE RADF3 (IDO, L1, CC, CH, WA1, WA2)
 
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C***BEGIN PROLOGUE  RADF3
 
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C***SUBSIDIARY
 
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C***PURPOSE  Calculate the fast Fourier transform of subvectors of
 
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C            length three.
 
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C***LIBRARY   SLATEC (FFTPACK)
 
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C***TYPE      SINGLE PRECISION (RADF3-S)
 
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C***AUTHOR  Swarztrauber, P. N., (NCAR)
 
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C***ROUTINES CALLED  (NONE)
 
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C***REVISION HISTORY  (YYMMDD)
 
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C   790601  DATE WRITTEN
 
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C   830401  Modified to use SLATEC library source file format.
 
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C   860115  Modified by Ron Boisvert to adhere to Fortran 77 by
 
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C           (a) changing dummy array size declarations (1) to (*),
 
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C           (b) changing definition of variable TAUI by using
 
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C               FORTRAN intrinsic function SQRT instead of a DATA
 
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C               statement.
 
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C   881128  Modified by Dick Valent to meet prologue standards.
 
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C   890831  Modified array declarations.  (WRB)
 
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C   891214  Prologue converted to Version 4.0 format.  (BAB)
 
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C   900402  Added TYPE section.  (WRB)
 
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C***END PROLOGUE  RADF3
 
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      DIMENSION CH(IDO,3,*), CC(IDO,L1,3), WA1(*), WA2(*)
 
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C***FIRST EXECUTABLE STATEMENT  RADF3
 
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      TAUR = -.5
 
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      TAUI = .5*SQRT(3.)
 
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      DO 101 K=1,L1
 
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         CR2 = CC(1,K,2)+CC(1,K,3)
 
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         CH(1,1,K) = CC(1,K,1)+CR2
 
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         CH(1,3,K) = TAUI*(CC(1,K,3)-CC(1,K,2))
 
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         CH(IDO,2,K) = CC(1,K,1)+TAUR*CR2
 
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  101 CONTINUE
 
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      IF (IDO .EQ. 1) RETURN
 
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      IDP2 = IDO+2
 
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      IF((IDO-1)/2.LT.L1) GO TO 104
 
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      DO 103 K=1,L1
 
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CDIR$ IVDEP
 
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         DO 102 I=3,IDO,2
 
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            IC = IDP2-I
 
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            DR2 = WA1(I-2)*CC(I-1,K,2)+WA1(I-1)*CC(I,K,2)
 
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            DI2 = WA1(I-2)*CC(I,K,2)-WA1(I-1)*CC(I-1,K,2)
 
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            DR3 = WA2(I-2)*CC(I-1,K,3)+WA2(I-1)*CC(I,K,3)
 
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            DI3 = WA2(I-2)*CC(I,K,3)-WA2(I-1)*CC(I-1,K,3)
 
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            CR2 = DR2+DR3
 
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            CI2 = DI2+DI3
 
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            CH(I-1,1,K) = CC(I-1,K,1)+CR2
 
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            CH(I,1,K) = CC(I,K,1)+CI2
 
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            TR2 = CC(I-1,K,1)+TAUR*CR2
 
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            TI2 = CC(I,K,1)+TAUR*CI2
 
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            TR3 = TAUI*(DI2-DI3)
 
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            TI3 = TAUI*(DR3-DR2)
 
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            CH(I-1,3,K) = TR2+TR3
 
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            CH(IC-1,2,K) = TR2-TR3
 
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            CH(I,3,K) = TI2+TI3
 
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            CH(IC,2,K) = TI3-TI2
 
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  102    CONTINUE
 
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  103 CONTINUE
 
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      RETURN
 
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  104 DO 106 I=3,IDO,2
 
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         IC = IDP2-I
 
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CDIR$ IVDEP
 
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         DO 105 K=1,L1
 
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            DR2 = WA1(I-2)*CC(I-1,K,2)+WA1(I-1)*CC(I,K,2)
 
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            DI2 = WA1(I-2)*CC(I,K,2)-WA1(I-1)*CC(I-1,K,2)
 
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            DR3 = WA2(I-2)*CC(I-1,K,3)+WA2(I-1)*CC(I,K,3)
 
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            DI3 = WA2(I-2)*CC(I,K,3)-WA2(I-1)*CC(I-1,K,3)
 
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            CR2 = DR2+DR3
 
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            CI2 = DI2+DI3
 
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            CH(I-1,1,K) = CC(I-1,K,1)+CR2
 
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            CH(I,1,K) = CC(I,K,1)+CI2
 
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            TR2 = CC(I-1,K,1)+TAUR*CR2
 
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            TI2 = CC(I,K,1)+TAUR*CI2
 
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            TR3 = TAUI*(DI2-DI3)
 
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            TI3 = TAUI*(DR3-DR2)
 
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            CH(I-1,3,K) = TR2+TR3
 
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            CH(IC-1,2,K) = TR2-TR3
 
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            CH(I,3,K) = TI2+TI3
 
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            CH(IC,2,K) = TI3-TI2
 
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  105    CONTINUE
 
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  106 CONTINUE
 
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      RETURN
 
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      END