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Text File  |  1989-08-14  |  1.8 KB  |  58 lines
  1. *deck passb4
  2.       subroutine passb4 (ido,l1,cc,ch,wa1,wa2,wa3)
  3. C***BEGIN PROLOGUE  PASSB4
  4. C***REFER TO CFFTB
  5. C***ROUTINES CALLED (NONE)
  6. C***END PROLOGUE  PASSB4
  7.       dimension       cc(ido,4,l1)           ,ch(ido,l1,4)           ,
  8.      1                wa1(1)     ,wa2(1)     ,wa3(1)
  9. C***FIRST EXECUTABLE STATEMENT  PASSB4
  10.       if (ido .ne. 2) go to 102
  11.       do 101 k=1,l1
  12.          ti1 = cc(2,1,k)-cc(2,3,k)
  13.          ti2 = cc(2,1,k)+cc(2,3,k)
  14.          tr4 = cc(2,4,k)-cc(2,2,k)
  15.          ti3 = cc(2,2,k)+cc(2,4,k)
  16.          tr1 = cc(1,1,k)-cc(1,3,k)
  17.          tr2 = cc(1,1,k)+cc(1,3,k)
  18.          ti4 = cc(1,2,k)-cc(1,4,k)
  19.          tr3 = cc(1,2,k)+cc(1,4,k)
  20.          ch(1,k,1) = tr2+tr3
  21.          ch(1,k,3) = tr2-tr3
  22.          ch(2,k,1) = ti2+ti3
  23.          ch(2,k,3) = ti2-ti3
  24.          ch(1,k,2) = tr1+tr4
  25.          ch(1,k,4) = tr1-tr4
  26.          ch(2,k,2) = ti1+ti4
  27.          ch(2,k,4) = ti1-ti4
  28.   101 continue
  29.       return
  30.   102 do 104 k=1,l1
  31.          do 103 i=2,ido,2
  32.             ti1 = cc(i,1,k)-cc(i,3,k)
  33.             ti2 = cc(i,1,k)+cc(i,3,k)
  34.             ti3 = cc(i,2,k)+cc(i,4,k)
  35.             tr4 = cc(i,4,k)-cc(i,2,k)
  36.             tr1 = cc(i-1,1,k)-cc(i-1,3,k)
  37.             tr2 = cc(i-1,1,k)+cc(i-1,3,k)
  38.             ti4 = cc(i-1,2,k)-cc(i-1,4,k)
  39.             tr3 = cc(i-1,2,k)+cc(i-1,4,k)
  40.             ch(i-1,k,1) = tr2+tr3
  41.             cr3 = tr2-tr3
  42.             ch(i,k,1) = ti2+ti3
  43.             ci3 = ti2-ti3
  44.             cr2 = tr1+tr4
  45.             cr4 = tr1-tr4
  46.             ci2 = ti1+ti4
  47.             ci4 = ti1-ti4
  48.             ch(i-1,k,2) = wa1(i-1)*cr2-wa1(i)*ci2
  49.             ch(i,k,2) = wa1(i-1)*ci2+wa1(i)*cr2
  50.             ch(i-1,k,3) = wa2(i-1)*cr3-wa2(i)*ci3
  51.             ch(i,k,3) = wa2(i-1)*ci3+wa2(i)*cr3
  52.             ch(i-1,k,4) = wa3(i-1)*cr4-wa3(i)*ci4
  53.             ch(i,k,4) = wa3(i-1)*ci4+wa3(i)*cr4
  54.   103    continue
  55.   104 continue
  56.       return
  57.       end
  58.