website/archive/binaries/mac/src/disembl/Tisean_3.0.1/source_f/slatec/radf4.f

   1 *DECK RADF4
   2       SUBROUTINE RADF4 (IDO, L1, CC, CH, WA1, WA2, WA3)
   3 C***BEGIN PROLOGUE  RADF4
   4 C***SUBSIDIARY
   5 C***PURPOSE  Calculate the fast Fourier transform of subvectors of
   6 C            length four.
   7 C***LIBRARY   SLATEC (FFTPACK)
   8 C***TYPE      SINGLE PRECISION (RADF4-S)
   9 C***AUTHOR  Swarztrauber, P. N., (NCAR)
  10 C***ROUTINES CALLED  (NONE)
  11 C***REVISION HISTORY  (YYMMDD)
  12 C   790601  DATE WRITTEN
  13 C   830401  Modified to use SLATEC library source file format.
  14 C   860115  Modified by Ron Boisvert to adhere to Fortran 77 by
  15 C           (a) changing dummy array size declarations (1) to (*).
  16 C           (b) changing definition of variable HSQT2 by using
  17 C               FORTRAN intrinsic function SQRT instead of a DATA
  18 C               statement.
  19 C   881128  Modified by Dick Valent to meet prologue standards.
  20 C   890831  Modified array declarations.  (WRB)
  21 C   891214  Prologue converted to Version 4.0 format.  (BAB)
  22 C   900402  Added TYPE section.  (WRB)
  23 C***END PROLOGUE  RADF4
  24       DIMENSION CC(IDO,L1,4), CH(IDO,4,*), WA1(*), WA2(*), WA3(*)
  25 C***FIRST EXECUTABLE STATEMENT  RADF4
  26       HSQT2 = .5*SQRT(2.)
  27       DO 101 K=1,L1
  28          TR1 = CC(1,K,2)+CC(1,K,4)
  29          TR2 = CC(1,K,1)+CC(1,K,3)
  30          CH(1,1,K) = TR1+TR2
  31          CH(IDO,4,K) = TR2-TR1
  32          CH(IDO,2,K) = CC(1,K,1)-CC(1,K,3)
  33          CH(1,3,K) = CC(1,K,4)-CC(1,K,2)
  34   101 CONTINUE
  35       IF (IDO-2) 107,105,102
  36   102 IDP2 = IDO+2
  37       IF((IDO-1)/2.LT.L1) GO TO 111
  38       DO 104 K=1,L1
  39 CDIR$ IVDEP
  40          DO 103 I=3,IDO,2
  41             IC = IDP2-I
  42             CR2 = WA1(I-2)*CC(I-1,K,2)+WA1(I-1)*CC(I,K,2)
  43             CI2 = WA1(I-2)*CC(I,K,2)-WA1(I-1)*CC(I-1,K,2)
  44             CR3 = WA2(I-2)*CC(I-1,K,3)+WA2(I-1)*CC(I,K,3)
  45             CI3 = WA2(I-2)*CC(I,K,3)-WA2(I-1)*CC(I-1,K,3)
  46             CR4 = WA3(I-2)*CC(I-1,K,4)+WA3(I-1)*CC(I,K,4)
  47             CI4 = WA3(I-2)*CC(I,K,4)-WA3(I-1)*CC(I-1,K,4)
  48             TR1 = CR2+CR4
  49             TR4 = CR4-CR2
  50             TI1 = CI2+CI4
  51             TI4 = CI2-CI4
  52             TI2 = CC(I,K,1)+CI3
  53             TI3 = CC(I,K,1)-CI3
  54             TR2 = CC(I-1,K,1)+CR3
  55             TR3 = CC(I-1,K,1)-CR3
  56             CH(I-1,1,K) = TR1+TR2
  57             CH(IC-1,4,K) = TR2-TR1
  58             CH(I,1,K) = TI1+TI2
  59             CH(IC,4,K) = TI1-TI2
  60             CH(I-1,3,K) = TI4+TR3
  61             CH(IC-1,2,K) = TR3-TI4
  62             CH(I,3,K) = TR4+TI3
  63             CH(IC,2,K) = TR4-TI3
  64   103    CONTINUE
  65   104 CONTINUE
  66       GO TO 110
  67   111 DO 109 I=3,IDO,2
  68          IC = IDP2-I
  69 CDIR$ IVDEP
  70          DO 108 K=1,L1
  71             CR2 = WA1(I-2)*CC(I-1,K,2)+WA1(I-1)*CC(I,K,2)
  72             CI2 = WA1(I-2)*CC(I,K,2)-WA1(I-1)*CC(I-1,K,2)
  73             CR3 = WA2(I-2)*CC(I-1,K,3)+WA2(I-1)*CC(I,K,3)
  74             CI3 = WA2(I-2)*CC(I,K,3)-WA2(I-1)*CC(I-1,K,3)
  75             CR4 = WA3(I-2)*CC(I-1,K,4)+WA3(I-1)*CC(I,K,4)
  76             CI4 = WA3(I-2)*CC(I,K,4)-WA3(I-1)*CC(I-1,K,4)
  77             TR1 = CR2+CR4
  78             TR4 = CR4-CR2
  79             TI1 = CI2+CI4
  80             TI4 = CI2-CI4
  81             TI2 = CC(I,K,1)+CI3
  82             TI3 = CC(I,K,1)-CI3
  83             TR2 = CC(I-1,K,1)+CR3
  84             TR3 = CC(I-1,K,1)-CR3
  85             CH(I-1,1,K) = TR1+TR2
  86             CH(IC-1,4,K) = TR2-TR1
  87             CH(I,1,K) = TI1+TI2
  88             CH(IC,4,K) = TI1-TI2
  89             CH(I-1,3,K) = TI4+TR3
  90             CH(IC-1,2,K) = TR3-TI4
  91             CH(I,3,K) = TR4+TI3
  92             CH(IC,2,K) = TR4-TI3
  93   108    CONTINUE
  94   109 CONTINUE
  95   110 IF (MOD(IDO,2) .EQ. 1) RETURN
  96   105 DO 106 K=1,L1
  97          TI1 = -HSQT2*(CC(IDO,K,2)+CC(IDO,K,4))
  98          TR1 = HSQT2*(CC(IDO,K,2)-CC(IDO,K,4))
  99          CH(IDO,1,K) = TR1+CC(IDO,K,1)
 100          CH(IDO,3,K) = CC(IDO,K,1)-TR1
 101          CH(1,2,K) = TI1-CC(IDO,K,3)
 102          CH(1,4,K) = TI1+CC(IDO,K,3)
 103   106 CONTINUE
 104   107 RETURN
 105       END