www.pudn.com > Fortran.zip > KFOUR.FOR, change:1995-03-31,size:429b

 
 
	SUBROUTINE KFOUR(F,N1,N2,A,B) 
	DIMENSION F(N2),A(N1),B(N1) 
	DOUBLE PRECISION F,A,B,C,S,T,C1,S1,U1,U2,U0 
	T=6.283185306/N2 
	C=COS(T) 
	S=SIN(T) 
	T=2.0/N2 
	C1=1.0 
	S1=0.0 
	DO 20 I=1,N1 
	  U1=0.0 
	  U2=0.0 
	  DO 10 J=N2,2,-1 
	    U0=F(J)+2.0*C1*U1-U2 
	    U2=U1 
	    U1=U0 
10        CONTINUE 
	  A(I)=T*(F(1)+U1*C1-U2) 
	  B(I)=T*U1*S1 
	  U0=C*C1-S*S1 
	  S1=C*S1+S*C1 
	  C1=U0 
20	CONTINUE 
	RETURN 
	END