--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/SbpOperators/boundaryops/normal_derivative.jl	Mon Dec 07 14:05:47 2020 +0100
@@ -0,0 +1,18 @@
+"""
+    NormalDerivative(grid::EquidistantGrid, closure_stencil::Stencil, boundary::CartesianBoundary)
+    NormalDerivative(grid::EquidistantGrid{1}, closure_stencil::Stencil, region::Region)
+
+Creates the normal derivative boundary operator `d` as a `TensorMapping`
+
+`d` is the normal derivative of a grid function at the boundary specified by `boundary` or `region` using some `closure_stencil`.
+`d'` is the prolongation of the normal derivative of a grid function to the whole grid using the same `closure_stencil`.
+On a one-dimensional `grid`, `d` is a `BoundaryOperator`. On a multi-dimensional `grid`, `d` is the inflation of
+a `BoundaryOperator`. Also see the documentation of `SbpOperators.boundary_operator(...)` for more details.
+"""
+function NormalDerivative(grid::EquidistantGrid, closure_stencil::Stencil, boundary::CartesianBoundary)
+    direction = dim(boundary)
+    h_inv = inverse_spacing(grid)[direction]
+    return SbpOperators.boundary_operator(grid, scale(closure_stencil,h_inv), boundary)
+end
+NormalDerivative(grid::EquidistantGrid{1}, closure_stencil::Stencil, region::Region) = NormalDerivative(grid, closure_stencil, CartesianBoundary{1,typeof(region)}())
+export NormalDerivative