--- a/sbpD2.jl	Thu Jan 10 14:46:15 2019 +0100
+++ b/sbpD2.jl	Thu Jan 10 15:49:44 2019 +0100
@@ -1,9 +1,33 @@
-struct D2{T}
+abstract type ConstantStencilOperator end
+
+function apply!(op::ConstantStencilOperator, u::AbstractVector, v::AbstractVector, h::Real, start::Int, N::Int; stride::Int=1)
+    cSize = closureSize(op)
+
+    for i ∈ range(start; length=cSize, step=stride)
+        u[i] = apply!(op.closureStencils[i], v, i; stride=stride)/h^2
+    end
+
+    innerStart = start + cSize*stride
+    innerEnd = N - cSize*stride-1
+    for i ∈ range(innerStart, stop=innerEnd, step=stride)
+        u[i] = apply(op.innerStencil, v, i; stride=stride)/h^2
+    end
+
+    for i ∈ range(innerEnd+1, length=cSize, step=cSize)
+        u[i] = op.parity*apply(flip(op.closureStencils[M-i+1]), v, i; stride=stride)/h^2
+    end
+end
+
+odd = -1
+even = 1
+
+struct D2{T} <: ConstantStencilOperator
     quadratureClosure::Vector{T}
     innerStencil::Stencil
     closureStencils::Vector{Stencil} # TBD: Should this be a tuple?
     eClosure::Vector{T}
     dClosure::Vector{T}
+    parity::Int
 end
 
 function closureSize(D::D2)::Int
@@ -34,6 +58,7 @@
         closureStencils,
         stringToVector(Float64, d["e"]),
         stringToVector(Float64, d["d1"]),
+        even
     )
 
     # Return d2!