! 
     PROGRAM P73
!
!
     IMPLICIT NONE
     REAL :: M1(3,4),M2(4,2),M3(3,2)
!
     INTERFACE
     SUBROUTINE MATSIN(M1,M2,I1,J1,I2,J2)
     IMPLICIT NONE
     REAL, INTENT(IN OUT) :: M1(:,:),M2(:,:)
     INTEGER, INTENT(IN) :: J1,J2,I1,I2
     END SUBROUTINE MATSIN
     END INTERFACE
!
     INTERFACE
     SUBROUTINE MULT(M1,M2,M3,I1,J1,J2)
     IMPLICIT NONE
     REAL, INTENT(IN OUT) :: M1(:,:),M2(:,:),M3(:,:)
     INTEGER, INTENT(IN) :: I1,J1,J2
     END SUBROUTINE MULT
     END INTERFACE
!
     INTERFACE
     SUBROUTINE PRNMAT(M3,IMAX,JMAX)
     IMPLICIT NONE
     REAL, INTENT(IN OUT) :: M3(:,:)
     INTEGER, INTENT(IN) :: IMAX,JMAX
     END SUBROUTINE PRNMAT
     END INTERFACE
!
     PRINT *,'This is Program P73 - Matrix multiplication'
     PRINT *,'PROGRAM IS READING DATA INTO ARRAYS'
     CALL MATSIN(M1,M2,3,4,4,2)
     CALL PRNMAT(M1,3,4)
     CALL PRNMAT(M2,4,2)
     PRINT *,'NOW MULTIPLYING MATRICES'
     CALL MULT(M1,M2,M3,3,4,2)
     PRINT *,'SOLUTION:'
     CALL PRNMAT(M3,3,2)
     STOP
     END PROGRAM P73
!
     SUBROUTINE MATSIN(M1,M2,I1,J1,I2,J2)
!
     IMPLICIT NONE
     REAL, INTENT(IN OUT) :: M1(:,:),M2(:,:)
     INTEGER, INTENT(IN) :: J1,J2,I1,I2
     INTEGER :: I,J
!
!     READ IN M1
!     ONE PER CARD
!
L1:   DO I=1,I1
         READ *,(M1(I,J),J=1,J1)
      END DO L1
!
!     READ IN M2
!     ONE ROW/CARD
!
LOOP:   DO I=1,I2
         READ *,(M2(I,J),J=1,J2)
        END DO LOOP
     RETURN
     END SUBROUTINE MATSIN
!
!
!
     SUBROUTINE MULT(M1,M2,M3,I1,J1,J2)
!
     IMPLICIT NONE
     REAL, INTENT(IN OUT) :: M1(:,:),M2(:,:),M3(:,:)
     INTEGER, INTENT(IN) :: J1,J2,I1
     INTEGER :: I,J,K
!
!      Now, we will multiply the two matrices
!
!
     M3=0.0
     DO K=1,J2
        DO I=1,J1
           DO J=1,I1
              M3(J,K) = M3(J,K) + M1(J,I) * M2(I,K)
           END DO
        END DO
     END DO
     RETURN
     END SUBROUTINE MULT
!
!
!
     SUBROUTINE PRNMAT(M3,IMAX,JMAX)
!
     IMPLICIT NONE
     REAL, INTENT(IN OUT) :: M3(:,:)
     INTEGER, INTENT(IN) :: IMAX,JMAX
     INTEGER :: I,J
!
!
L3:   DO I=1,IMAX
         PRINT *,(M3(I,J),J=1,JMAX)
      END DO L3
      PRINT *,' '
!
      RETURN
      END SUBROUTINE PRNMAT