SUBROUTINE COSTI (N,WSAVE) DIMENSION WSAVE(1) DATA PI /3.14159265358979/ IF (N .LE. 3) RETURN NM1 = N-1 NP1 = N+1 NS2 = N/2 DT = PI/FLOAT(NM1) FK = 0. DO 101 K=2,NS2 KC = NP1-K FK = FK+1. WSAVE(K) = 2.*SIN(FK*DT) WSAVE(KC) = 2.*COS(FK*DT) 101 CONTINUE CALL RFFTI (NM1,WSAVE(N+1)) RETURN END