subroutine scsqf1 (n,x,w,xh) real x(1), w(1), xh(1), xim1 c ns2 = (n+1)/2 np2 = n+2 do 101 k=2,ns2 kc = np2-k xh(k) = x(k)+x(kc) xh(kc) = x(k)-x(kc) 101 continue modn = mod(n,2) if (modn .eq. 0) xh(ns2+1) = x(ns2+1)+x(ns2+1) c do 102 k=2,ns2 kc = np2-k x(k) = w(k-1)*xh(kc)+w(kc-1)*xh(k) x(kc) = w(k-1)*xh(k)-w(kc-1)*xh(kc) 102 continue if (modn .eq. 0) x(ns2+1) = w(ns2)*xh(ns2+1) c call srfftf (n,x,xh) c do 103 i=3,n,2 xim1 = x(i-1)-x(i) x(i) = x(i-1)+x(i) x(i-1) = xim1 103 continue c return end