simlin_from_net.f

C	FIND SOLUTION USING GAUSS ELIMINATION	BY PIVOTING METHOD
	DIMENSION A(10,11), X(10)
	WRITE (*,*) 'ENTER THE DIMENSION OF THE SYSTEM'
	READ (*,*) N
	WRITE (*,*) 'ENTER THE ELEMENTS OF BOTH A AND PRODUCT MATRIX'
	WRITE (*,*) '(ROW-WISE)'
	READ (*,*) ((A(I,J), J=1,N+1), I=1,N)
	DO 10 K=1,N-1
	CALL INTERCHANGE(N,A,K)
	PIVOT = A(K,K)
	DO 20 I=K+1,N
	FACTOR = A(I,K)/PIVOT
	DO 30 J=1,N+1
	A(I,J) = A(I,J) - FACTOR*A(K,J)
  30    CONTINUE
  20    CONTINUE
  10    CONTINUE
C	********** BACK SUBSTITUTION **********
	X(N) = A(N,N+1)/A(N,N)
	DO 40 K=N-1,1,-1
	SUMM=0
	DO 50 J=K+1,N
	SUMM = SUMM + A(K,J)*X(J)
  50    CONTINUE
        X(K) = (A(K,N+1)-SUMM)/A(K,K)
  40    CONTINUE
C	********** RESULT **********
	WRITE (*,*) 'THE SOLUTION VECTOR IS:'
	DO I=1,N
	WRITE (*,60) I,X(I)
	END DO
  60    FORMAT ("X(",I2,")",F7.2)
	STOP
	END
C	SUBROUTINE TO FIND THE LARGEST NO. & INTERCHANGE THE ROWS
C	***** TO FIND THE LARGEST ELEMENT IN THE COLUMN *****
	SUBROUTINE INTERCHANGE (N,A,K)
	DIMENSION A(10,11)
	INTEGER ROW
	ROW = K
	LARGE = ABS (A(K,K))
	DO 5 I=K+1,N
	IF (ABS(A(I,K)) .GT. ABS(A(K,K))) THEN
	LARGE = ABS(A(I,K))
	ROW = I
	END IF
  5     CONTINUE
C	***** INTERCHANGING THE ITH ROW WITH KTH ROW *****
	IF (ROW .NE. K) THEN
	DO 6 J=1,N+1
	TEMP = A(ROW,J)
	A(ROW,J) = A(K,J)
	A(K,J) = TEMP
  6     CONTINUE
	END IF
	RETURN
	END