SUBROUTINE COSQF1 (N,X,W,XH) DIMENSION X(1) ,W(1) ,XH(1) 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) 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) CALL RFFTF (N,X,XH) 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 RETURN END