P73.F90

Matrix multiplication

! =====> Program - P141.F90
!
!
!
!
!
     REAL M1(3,4),M2(4,2),M3(3,2)
!
     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,M3,3,4,4,2)
     PRINT *,'SOLUTION:'
     CALL PRNMAT(M3,3,2)
     STOP
     END


SUBROUTINE MATSIN(M1,M2,I1,J1,I2,J2)
     REAL M1(I1,J1), M2(I2,J2)
!
!     Tell program where data for  READ   is coming from
      OPEN(UNIT=5, FILE='P73.DAT')      ! UNIT=5 is the default input
!
!     READ IN M1
!     ONE PER CARD
!
L1:   DO I=1,I1
         READ 27,(M1(I,J),J=1,J1)
      END DO L1
27   FORMAT(8(F5.2))
!
!     READ IN M2
!     ONE ROW/CARD
!
L1:   DO I=1,I2
         READ 27,(M2(I,J),J=1,J2)
      END DO L1
     RETURN
     END
!
!
!
SUBROUTINE MULT(M1,M2,M3,I1,J1,I2,J2)
     REAL M1(I1,J1),M2(I2,J2),M3(I1,J2)
! 
!      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 PRNMAT(M3,IMAX,JMAX)
!
     REAL M3(IMAX,JMAX)
!
!
L3:   DO I=1,IMAX
         PRINT 202, (M3(I,J),J=1,JMAX)
      END DO L3
202   FORMAT(8(2X,F8.3))
      PRINT *,' '
!
      RETURN
      END

DATA:
45.3 23.O 63.7 2.1
 54.6 3.4 64.6 3.3
 75.7 25.3 45.8 74.3
 45.7 9.0 
 2.3 67.2
 4.9 23.4
 54.2 2.9

OUTPUT:
Program entered
 This is Program P73 - Matrix multiplication
 PROGRAM IS READING DATA INTO ARRAYS
    45.300    23.000    63.700     2.100  
    54.600     3.400    64.600     3.300  
    75.700    25.300    45.800    74.300  
  
    45.700     9.000  
     2.300    67.200  
     4.900    23.400  
    54.200     2.900  
  
 NOW MULTIPLYING MATRICES
 SOLUTION:
  2549.060  3449.970  
  2998.440  2241.090  
  7769.160  3668.650  
  
Fortran-90 STOP

Page builder: Charles Boivin

Last modified: 11/07/95