PROGRAM MATMUL_TIME
      PARAMETER (SIZE=1000)
      REAL*8 A(SIZE, SIZE), B(SIZE, SIZE), C(SIZE, SIZE), AROW(SIZE)
      REAL MFLOPS0, MFLOPS1
C
      PRINT *, 'ENTER N: '
      READ(*,*) N
      IF ( N.GT.SIZE ) THEN
         PRINT *, 'N TOO LARGE.'
         STOP
      ENDIF
*
      CALL MATMUL0(N, A, B, C, MFLOPS0)
      CALL MATMUL1(N, A, B, C, AROW, MFLOPS1)
*
      PRINT *, 'N = ', N, '   MFLOPS0 = ', MFLOPS0,
     +         '   MFLOPS1 = ', MFLOPS1
      STOP
      END
C
C----------------------------------------------------------------------
C
      SUBROUTINE MATMUL0(N, A, B, C, MFLOPS)
      REAL*8 A(N,N), B(N,N), C(N,N)
      REAL WALLTIME, MFLOPS
      REAL ETIME
      REAL TARRAY(2), TIME0, TIME1, TIME2
C
      NTIMES = 100000000/(N*N*(2*N-1))
      IF ( NTIMES .EQ. 0 ) NTIMES = 1
C
      DO J = 1, N
      DO I = 1, N
         A(I,J) = 1.0
         B(I,J) = 1.0
      ENDDO
      ENDDO
C
      TIME0 = ETIME(TARRAY)
      DO L = 1, NTIMES
         DO J = 1, N
            DO I = 1, N
               C(I,J) = 0.0
            ENDDO
         ENDDO
         DO I = 1, N
            DO J = 1, N
               DO K = 1, N
                  C(I,J) = C(I,J) + A(I,K) * B(K,J)
               ENDDO
            ENDDO
         ENDDO
         CALL DUMMY(C)
      ENDDO
      TIME1 = ETIME(TARRAY)
      DO I = 1, NTIMES
         CALL DUMMY(C)
      ENDDO
      TIME2 = ETIME(TARRAY)
C
      WALLTIME = ((TIME1 - TIME0) - (TIME2 - TIME1)) / REAL(NTIMES)
      MFLOPS = (N*N*(2*N-1)) / (WALLTIME * 1.0E+06)
*
C     PRINT *, "C(1,1) = ", C(1,1)
      RETURN
      END
C
C----------------------------------------------------------------------
C
      SUBROUTINE MATMUL1(N, A, B, C, AROW, MFLOPS)
      REAL*8 A(N,N), B(N,N), C(N,N), AROW(N)
      REAL WALLTIME, MFLOPS
      REAL ETIME
      REAL TARRAY(2), TIME0, TIME1, TIME2
C
      NTIMES = 500000000/(N*N*(2*N-1))
      IF ( NTIMES .EQ. 0 ) NTIMES = 1
C
      DO J = 1, N
      DO I = 1, N
         A(I,J) = 1.0
         B(I,J) = 1.0
      ENDDO
      ENDDO
C
      TIME0 = ETIME(TARRAY)
      DO L = 1, NTIMES
         DO J = 1, N
            DO I = 1, N
               C(I,J) = 0.0
            ENDDO
         ENDDO
         DO I = 1, N
            DO K = 1, N
               AROW(K) = A(I,K)
            ENDDO
            DO J = 1, N
               DO K = 1, N
                  C(I,J) = C(I,J) + AROW(K) * B(K,J)
               ENDDO
            ENDDO
         ENDDO
         CALL DUMMY(C)
      ENDDO
      TIME1 = ETIME(TARRAY)
      DO I = 1, NTIMES
         CALL DUMMY(C)
      ENDDO
      TIME2 = ETIME(TARRAY)
C
      WALLTIME = ((TIME1 - TIME0) - (TIME2 - TIME1)) / REAL(NTIMES)
      MFLOPS = (N*N*(2*N-1)) / (WALLTIME * 1.0E+06)
C
C     PRINT *, "C(1,1) = ", C(1,1)
      RETURN
      END
C
C----------------------------------------------------------------------
C
      SUBROUTINE DUMMY(C)
      DOUBLE PRECISION C
      RETURN
      END