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Text File  |  1996-07-19  |  1KB  |  44 lines
  1.       subroutine passb3 (ido,l1,cc,ch,wa1,wa2)
  2.       implicit double precision (a-h,o-z)
  3.       dimension       cc(ido,3,l1)           ,ch(ido,l1,3)           ,
  4.      1                wa1(1)     ,wa2(1)
  5.       data taur,taui /-.5,.866025403784439/
  6.       if (ido .ne. 2) go to 102
  7.       do 101 k=1,l1
  8.          tr2 = cc(1,2,k)+cc(1,3,k)
  9.          cr2 = cc(1,1,k)+taur*tr2
  10.          ch(1,k,1) = cc(1,1,k)+tr2
  11.          ti2 = cc(2,2,k)+cc(2,3,k)
  12.          ci2 = cc(2,1,k)+taur*ti2
  13.          ch(2,k,1) = cc(2,1,k)+ti2
  14.          cr3 = taui*(cc(1,2,k)-cc(1,3,k))
  15.          ci3 = taui*(cc(2,2,k)-cc(2,3,k))
  16.          ch(1,k,2) = cr2-ci3
  17.          ch(1,k,3) = cr2+ci3
  18.          ch(2,k,2) = ci2+cr3
  19.          ch(2,k,3) = ci2-cr3
  20.   101 continue
  21.       return
  22.   102 do 104 k=1,l1
  23.          do 103 i=2,ido,2
  24.             tr2 = cc(i-1,2,k)+cc(i-1,3,k)
  25.             cr2 = cc(i-1,1,k)+taur*tr2
  26.             ch(i-1,k,1) = cc(i-1,1,k)+tr2
  27.             ti2 = cc(i,2,k)+cc(i,3,k)
  28.             ci2 = cc(i,1,k)+taur*ti2
  29.             ch(i,k,1) = cc(i,1,k)+ti2
  30.             cr3 = taui*(cc(i-1,2,k)-cc(i-1,3,k))
  31.             ci3 = taui*(cc(i,2,k)-cc(i,3,k))
  32.             dr2 = cr2-ci3
  33.             dr3 = cr2+ci3
  34.             di2 = ci2+cr3
  35.             di3 = ci2-cr3
  36.             ch(i,k,2) = wa1(i-1)*di2+wa1(i)*dr2
  37.             ch(i-1,k,2) = wa1(i-1)*dr2-wa1(i)*di2
  38.             ch(i,k,3) = wa2(i-1)*di3+wa2(i)*dr3
  39.             ch(i-1,k,3) = wa2(i-1)*dr3-wa2(i)*di3
  40.   103    continue
  41.   104 continue
  42.       return
  43.       end
  44.