--- a/src/SbpOperators/volumeops/derivatives/second_derivative.jl	Tue Apr 04 21:46:06 2023 +0200
+++ b/src/SbpOperators/volumeops/derivatives/second_derivative.jl	Sat May 20 14:33:25 2023 +0200
@@ -1,48 +1,37 @@
 """
-    second_derivative(grid::EquidistantGrid, inner_stencil, closure_stencils, direction)
-
-Creates the second-derivative operator `D2` as a `LazyTensor`
+    second_derivative(g::EquidistantGrid, stencil_set, direction)
 
-`D2` approximates the second-derivative d²/dξ² on `grid` along the coordinate dimension specified by
-`direction`, using the stencil `inner_stencil` in the interior and a set of stencils `closure_stencils`
-for the points in the closure regions.
+Creates the second derivative operator `D2` as a `LazyTensor`
 
-On a one-dimensional `grid`, `D2` is a `VolumeOperator`. On a multi-dimensional `grid`, `D2` is the inflation of
-a `VolumeOperator`.
+`D2` approximates the second-derivative d²/dξ² on `g` along the coordinate
+dimension specified by `direction`.
 
 See also: [`VolumeOperator`](@ref), [`LazyTensors.inflate`](@ref).
 """
-function second_derivative(grid::EquidistantGrid, inner_stencil, closure_stencils, direction)
-    h_inv = inverse_spacing(grid)[direction]
-
-    D₂ = VolumeOperator(restrict(grid, direction), scale(inner_stencil,h_inv^2), scale.(closure_stencils,h_inv^2), even)
-    return LazyTensors.inflate(D₂, size(grid), direction)
+function second_derivative(g::TensorGrid, stencil_set, direction)
+    D₂ = second_derivative(g.grids[direction], stencil_set)
+    return LazyTensors.inflate(D₂, size(g), direction)
 end
 
-
-"""
-    second_derivative(grid, inner_stencil, closure_stencils)
-
-Creates a `second_derivative` operator on a 1D `grid` given `inner_stencil` and `closure_stencils`.
-"""
-second_derivative(grid::EquidistantGrid{1}, inner_stencil::Stencil, closure_stencils) = second_derivative(grid, inner_stencil, closure_stencils,1)
-
-
 """
-    second_derivative(grid, stencil_set, direction)
+    second_derivative(g::EquidistantGrid, stencil_set::::StencilSet)
 
-Creates a `second_derivative` operator on `grid` along coordinate dimension `direction` given a `stencil_set`.
+The second derivative operator on an `EquidistantGrid`. 
+Uses the `D2` stencil in `stencil_set`.
 """
-function second_derivative(grid::EquidistantGrid, stencil_set::StencilSet, direction)
+function second_derivative(g::EquidistantGrid, stencil_set::StencilSet)
     inner_stencil = parse_stencil(stencil_set["D2"]["inner_stencil"])
     closure_stencils = parse_stencil.(stencil_set["D2"]["closure_stencils"])
-    second_derivative(grid,inner_stencil,closure_stencils,direction);
+    return second_derivative(g, inner_stencil, closure_stencils)
 end
 
-
 """
-    second_derivative(grid, stencil_set)
+    second_derivative(g::EquidistantGrid, inner_stencil::Stencil, closure_stencils)
 
-Creates a `second_derivative` operator on a 1D `grid` given a `stencil_set`.
+The second derivative operator on an `EquidistantGrid`, given `inner_stencil` and
+`closure_stencils`.
 """
-second_derivative(grid::EquidistantGrid{1}, stencil_set::StencilSet) = second_derivative(grid, stencil_set, 1)
\ No newline at end of file
+function second_derivative(g::EquidistantGrid, inner_stencil::Stencil, closure_stencils)
+    h⁻¹ = inverse_spacing(g)
+    return VolumeOperator(g, scale(inner_stencil,h⁻¹^2), scale.(closure_stencils,h⁻¹^2), even)
+end