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Text File  |  1996-07-19  |  803b  |  25 lines
  1.       subroutine passb2 (ido,l1,cc,ch,wa1)
  2.       implicit double precision (a-h,o-z)
  3.       dimension       cc(ido,2,l1)           ,ch(ido,l1,2)           ,
  4.      1                wa1(1)
  5.       if (ido .gt. 2) go to 102
  6.       do 101 k=1,l1
  7.          ch(1,k,1) = cc(1,1,k)+cc(1,2,k)
  8.          ch(1,k,2) = cc(1,1,k)-cc(1,2,k)
  9.          ch(2,k,1) = cc(2,1,k)+cc(2,2,k)
  10.          ch(2,k,2) = cc(2,1,k)-cc(2,2,k)
  11.   101 continue
  12.       return
  13.   102 do 104 k=1,l1
  14.          do 103 i=2,ido,2
  15.             ch(i-1,k,1) = cc(i-1,1,k)+cc(i-1,2,k)
  16.             tr2 = cc(i-1,1,k)-cc(i-1,2,k)
  17.             ch(i,k,1) = cc(i,1,k)+cc(i,2,k)
  18.             ti2 = cc(i,1,k)-cc(i,2,k)
  19.             ch(i,k,2) = wa1(i-1)*ti2+wa1(i)*tr2
  20.             ch(i-1,k,2) = wa1(i-1)*tr2-wa1(i)*ti2
  21.   103    continue
  22.   104 continue
  23.       return
  24.       end
  25.