program matrix_multi33
      implicit none
      integer i, j, k
      real a(3,3), b(3,3), c(3,3)

      write(*,*) 'This code read in 3x3 matrix from a.dat and b.dat',
     &' then print out the results on screen.'

      open(unit=10,file='a.dat',status='OLD')
      write(*,*) 'The a.dat matrix is:'
      do i=1,3
        read(10,*) (a(i,j), j=1,3)
        write(*,*) (a(i,j), j=1,3)
      end do
      close(10)

      open(unit=20,file='b.dat',status='OLD')
      write(*,*) 'The b.dat matrix is:'
      do i=1,3
        read(20,*) (b(i,j), j=1,3)
        write(*,*) (b(i,j), j=1,3)
      end do
      close(20)

      do i=1,3
        do j=1,3
          do k=1,3
            c(i,j) = a(i,k) * b(k,j)
          end do
        end do
      end do

      write(*,*)
      write(*,*) 'The resulting matrix is:'
      write(*,*)
      do i=1,3
        write(*,*) c(i,1), c(i,2), c(i,3)
      end do

      end