det A    = sum on i=1...N:(-1)**(i+1) a_i1 det ||A||_i1

integer, parameter :: rk= selected_real_kind(6)
end module prec


module lap
  use prec
implicit none

contains
  recursive function det(a,n) result (d)
    real(kind=rk), intent(in), dimension(n,n) :: a
    real(kind=rk), dimension(n-1,n-1) :: b
  real(kind=rk) :: d
  integer ::i
  integer, intent(in)::n



if (size(a) > 4) then
  do i=1,n
 b(1:(i-1),:) = a(1:(i-1),:)
 b(i:n,:) = a((i+1):n,:)
 b(:,:) = a(:,2:n)
    d= ((-1)**(i+1))*a(i,1)*det(b,n)
end do
    else
      d = a(1,1)*a(2,2)-a(1,2)*a(2,1)

      end if
  end function det
end module lap




      program sistema

b(1:(i-1),:) = a(1:(i-1),2:n)
b(i:n,:) = a((i+1):n,2:n)