module amg_d_pde2d_base_mod
  use psb_base_mod, only : psb_dpk_, dzero, done
  real(psb_dpk_), save, private :: epsilon=done/80
contains
  subroutine pde_set_parm(dat)
    real(psb_dpk_), intent(in) :: dat
    epsilon = dat
  end subroutine pde_set_parm
  !
  ! functions parametrizing the differential equation
  !
  function b1(x,y)
    use psb_base_mod, only : psb_dpk_, dzero, done
    real(psb_dpk_) :: b1
    real(psb_dpk_), intent(in) :: x,y
    b1 = dzero/1.414_psb_dpk_
  end function b1
  function b2(x,y)
    use psb_base_mod, only : psb_dpk_, dzero, done
    real(psb_dpk_) ::  b2
    real(psb_dpk_), intent(in) :: x,y
    b2 = dzero/1.414_psb_dpk_
  end function b2
  function c(x,y)
    use psb_base_mod, only : psb_dpk_, dzero, done
    real(psb_dpk_) ::  c
    real(psb_dpk_), intent(in) :: x,y
    c = dzero
  end function c
  function a1(x,y)
    use psb_base_mod, only : psb_dpk_, dzero, done
    real(psb_dpk_) ::  a1
    real(psb_dpk_), intent(in) :: x,y
    a1=done*epsilon
  end function a1
  function a2(x,y)
    use psb_base_mod, only : psb_dpk_, dzero, done
    real(psb_dpk_) ::  a2
    real(psb_dpk_), intent(in) :: x,y
    a2=done*epsilon
  end function a2
  function g(x,y)
    use psb_base_mod, only : psb_dpk_, dzero, done
    real(psb_dpk_) ::  g
    real(psb_dpk_), intent(in) :: x,y
    g = dzero
    if (x == done) then
      g = done
    else if (x == dzero) then
      g = done
    end if
  end function g
end module amg_d_pde2d_base_mod