Example 7.3

FORTRAN Version

! 
     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

45. 23. 63. 2.
54. 3. 64. 3.
75. 25. 45. 74.
45. 9. 
2. 67.
4. 23.
54. 2.

              +--------------------------------------------------+
              |     32-bit Power for Lahey Computer Systems      |
              |   Phar Lap's 386|DOS-Extender(tm) Version 7.0    |
              |  Copyright (C) 1986-94 Phar Lap Software, Inc.   |
              |           Available Memory = 14880 Kb            |
              +--------------------------------------------------+


This is Program P73 - Matrix multiplication
PROGRAM IS READING DATA INTO ARRAYS
    45.0000        23.0000        63.0000        2.00000    
    54.0000        3.00000        64.0000        3.00000    
    75.0000        25.0000        45.0000        74.0000    
 
    45.0000        9.00000    
    2.00000        67.0000    
    4.00000        23.0000    
    54.0000        2.00000    
 
NOW MULTIPLYING MATRICES
SOLUTION:
    2431.00        3399.00    
    2854.00        2165.00    
    7601.00        3533.00    
 

Last modified: 08/07/97