C=------- CS 5 GAUSSIAN ELIMINATION ---------------------------------
C GAUSSIAN ELIMINATION.
      TEST (N=4)
      DIMENSION (A(N,N), B(N), X(N))
      INPUT (A,B)
C
C ELIMINATION.
      FOR K = 1 TO N-1 BY 1
          FOR I = K+1 TO N BY 1
              AMULT = A(I,K)/A(K,K)
              FOR J = K+1 TO N BY 1
                  A(I,J) = A(I,J) - AMULT*A(K,J)
                  END (J)
              B(I) = B(I) - AMULT*B(K)
              END (I)
          END (K)
C
C BACK SUBSTITUTION.
      FOR I = N TO 1 BY -1
          X(I) = (B(I) - SUMMATION (A(I,J)*X(J),J=I+1 TO N))/A(I,I)
          END (I)
      OUTPUT (X)
      *STOP
