subroutine scfti1 (n,wa,ifac) real wa(1), arg, argh, argld, fi, tpi integer ifac(1), ntryh(4) data ntryh(1), ntryh(2), ntryh(3), ntryh(4) /3, 4, 2, 5/ data tpi / 6.2831853071 7958647692 5286766559 00577e0/ c nl = n nf = 0 j = 0 c 101 j = j+1 if (j.le.4) ntry = ntryh(j) if (j.gt.4) ntry = ntry + 2 104 nq = nl/ntry nr = nl-ntry*nq if (nr.ne.0) go to 101 c 105 nf = nf+1 ifac(nf+2) = ntry nl = nq if (ntry .ne. 2) go to 107 if (nf .eq. 1) go to 107 do 106 i=2,nf ib = nf-i+2 ifac(ib+2) = ifac(ib+1) 106 continue ifac(3) = 2 c 107 if (nl .ne. 1) go to 104 c ifac(1) = n ifac(2) = nf c argh = tpi/float(n) i = 2 l1 = 1 do 110 k1=1,nf ip = ifac(k1+2) ld = 0 l2 = l1*ip ido = n/l2 idot = ido+ido+2 ipm = ip-1 c do 109 j=1,ipm i1 = i wa(i-1) = 1.e0 wa(i) = 0.e0 ld = ld+l1 fi = 0.e0 argld = float(ld)*argh do 108 ii=4,idot,2 i = i+2 fi = fi+1.e0 arg = fi*argld wa(i-1) = cos(arg) wa(i) = sin(arg) 108 continue if (ip .le. 5) go to 109 wa(i1-1) = wa(i-1) wa(i1) = wa(i) 109 continue c l1 = l2 110 continue c return end