program iloczyn_macierzy
implicit none

real, dimension(4,4) :: a, b, c
integer :: i, j, k

do i = 1, 4
   do j = 1, 4
      write(*,*)'Wpisz element', i,j, 'pierwszej macierzy'
      read(*,*) a(i,j)
   end do
end do

write(*,*)'Wpisana macierz ma postac:'

do i = 1, 4
   write(*,*) (a(i,j), j = 1,4)
end do


do i = 1, 4
   do j = 1, 4
      write(*,*)'Wpisz element', i,j, 'drugiej macierzy'
      read(*,*) b(i,j)
   end do
end do

write(*,*)'Wpisana macierz ma postac:'

do i = 1, 4
   write(*,*) (b(i,j), j = 1,4)
end do


do i = 1, 4
   do j = 1, 4
      do k = 1, 4

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

write(*,*)'Iloczyn ma postac:'

do i = 1, 4
   write(*,*) (c(i,j), j = 1,4)
end do

!zamiast pisac samemu mozna skorzystac z gotowej
!funkcji mnozaczej dwie macierze a, b
! o nazwie matmul(a, b)


c = matmul(a,b) 

write(*,*)'Iloczyn ma postac:'

do i = 1, 4
   write(*,*) (c(i,j), j = 1,4)
end do

end