Fortran 95 source code to compute the product of matrix and vetor.

mv_product.f95

!****************************************************
! 行列とベクトルの積を計算
! : y = A x
!
! date          name            version
! 2018.08.15    mk-mode.com     1.00 新規作成
!
! Copyright(C) 2018 mk-mode.com All Rights Reserved.
!****************************************************
!
program mv_product
  implicit none
  integer :: i, j, n
  integer, parameter :: nmax = 100
  real(kind=8) :: a(nmax, nmax), x(nmax), y(nmax), tmp

  write (*,*) 'Input a dimension:'
  read (*,*) n

  write (*,*) 'Input a vector:'
  read (*,*) (x(i), i = 1, n)

  write (*,*) 'Input a matrix:'
  do i = 1, n
    read (*,*) (a(i, j), j = 1, n)
  end do

  ! 組み込み関数を使用しない場合
  !do i = 1, n
  !  tmp = 0
  !  do j = 1, n
  !    tmp = tmp + a(i, j) * x(j)
  !  end do
  !  y(i) = tmp
  !end do
  !
  ! 組み込み関数を使用する場合
  y(1:n) = matmul(a(1:n, 1:n), x(1:n))

  write (*,*) (y(i), i = 1, n)

  stop
end program mv_product