subroutine dpssf2 (ido,l1,cc,ch,wa1) double precision cc(ido,2,l1), ch(ido,l1,2), wa1(1), ti2, tr2 c if (ido .gt. 2) go to 102 do 101 k=1,l1 ch(1,k,1) = cc(1,1,k)+cc(1,2,k) ch(1,k,2) = cc(1,1,k)-cc(1,2,k) ch(2,k,1) = cc(2,1,k)+cc(2,2,k) ch(2,k,2) = cc(2,1,k)-cc(2,2,k) 101 continue return c 102 do 104 k=1,l1 do 103 i=2,ido,2 ch(i-1,k,1) = cc(i-1,1,k)+cc(i-1,2,k) tr2 = cc(i-1,1,k)-cc(i-1,2,k) ch(i,k,1) = cc(i,1,k)+cc(i,2,k) ti2 = cc(i,1,k)-cc(i,2,k) ch(i,k,2) = wa1(i-1)*ti2-wa1(i)*tr2 ch(i-1,k,2) = wa1(i-1)*tr2+wa1(i)*ti2 103 continue 104 continue c return end