www.pudn.com > Fortran.zip > AGRAD.FOR, change:1994-06-12,size:651b

 
	SUBROUTINE AGRAD(A,N,B,EPS,X,P,R,S,Q) 
	DIMENSION A(N,N),B(N),X(N),P(N),R(N),S(N),Q(N) 
	DOUBLE PRECISION A,B,X,P,R,S,Q,ALPHA,BETA,D,E 
	DO 10 I=1,N 
	  X(I)=0.0 
	  P(I)=B(I) 
	  R(I)=B(I) 
10	CONTINUE 
	I=1 
20	CALL BRMUL(A,P,N,N,1,S) 
	D=0.0 
	E=0.0 
	DO 30 K=1,N 
	  D=D+P(K)*B(K) 
	  E=E+P(K)*S(K) 
30	CONTINUE 
	ALPHA=D/E 
	DO 40 K=1,N 
40	X(K)=X(K)+ALPHA*P(K) 
	CALL BRMUL(A,X,N,N,1,Q) 
	D=0.0 
	DO 50 K=1,N 
	  R(K)=B(K)-Q(K) 
	  D=D+R(K)*S(K) 
50	CONTINUE 
	BETA=D/E 
	D=0.0 
	DO 55 K=1,N 
55	D=D+R(K)*R(K) 
	D=SQRT(D) 
	IF (D.LT.EPS) RETURN 
	DO 60 K=1,N 
60	P(K)=R(K)-BETA*P(K) 
	I=I+1 
	IF (I.LE.N) GOTO 20 
	RETURN 
	END