simplified coefficient function handling

Author: ChrisRackauckas

src/derivative_operators/abstract_operator_functions.jl

@@ -128,7 +128,7 @@ Base.:/(A::AbstractDerivativeOperator, B::AbstractVecOrMat) = Array(A) / B
     The Inf opnorm can be calculated easily using the stencil coeffiicents, while other opnorms
     default to compute from the full matrix form.
 =#
-function LinearAlgebra.opnorm(A::DerivativeOperator{T,S}, p::Real=2) where {T,S}
+function LinearAlgebra.opnorm(A::DerivativeOperator, p::Real=2)
     if p == Inf
         sum(abs.(A.stencil_coefs)) / A.dx^A.derivative_order
     else
@@ -167,6 +167,23 @@ end
 
 ################################################################################
 
+function *(coeff_func::Function, A::DerivativeOperator{T}) where T
+    coefficients = A.coefficients === nothing ? Vector{T}(undef,A.len) : A.coefficients
+    DerivativeOperator{T,typeof(A.dx),typeof(A.stencil_coefs),
+                       typeof(A.low_boundary_coefs),typeof(coefficients),
+                       typeof(coeff_func)}(
+        A.derivative_order, A.approximation_order,
+        A.dx, A.len, A.stencil_length,
+        A.stencil_coefs,
+        A.boundary_stencil_length,
+        A.boundary_point_count,
+        A.low_boundary_coefs,
+        A.high_boundary_coefs,coefficients,coeff_func,A.use_winding
+        )
+end
+
+################################################################################
+
 function DiffEqBase.update_coefficients!(A::AbstractDerivativeOperator,u,p,t)
     if A.coeff_func !== nothing
         A.coeff_func(A.coefficients,u,p,t)

src/derivative_operators/derivative_operator.jl

@@ -16,7 +16,7 @@ end
 
 function CenteredDifference(derivative_order::Int,
                             approximation_order::Int, dx::T,
-                            len::Int) where {T<:Real}
+                            len::Int, coeff_func=nothing) where {T<:Real}
 
     stencil_length          = derivative_order + approximation_order - 1 + (derivative_order+approximation_order)%2
     boundary_stencil_length = derivative_order + approximation_order
@@ -32,21 +32,22 @@ function CenteredDifference(derivative_order::Int,
     low_boundary_coefs      = convert(SVector{boundary_point_count},_low_boundary_coefs)
     high_boundary_coefs     = convert(SVector{boundary_point_count},reverse(SVector{boundary_stencil_length, T}[reverse(low_boundary_coefs[i]) for i in 1:boundary_point_count]))
 
+    coefficients            = coeff_func isa Nothing ? nothing : Vector{T}(undef,len)
     DerivativeOperator{T,T,typeof(stencil_coefs),
-                       typeof(low_boundary_coefs),Nothing,
-                       Nothing}(
+                       typeof(low_boundary_coefs),typeof(coefficients),
+                       typeof(coeff_func)}(
         derivative_order, approximation_order, dx, len, stencil_length,
         stencil_coefs,
         boundary_stencil_length,
         boundary_point_count,
         low_boundary_coefs,
-        high_boundary_coefs,nothing,nothing,false
+        high_boundary_coefs,coefficients,coeff_func,false
         )
 end
 
 function CenteredDifference(derivative_order::Int,
                             approximation_order::Int, dx::AbstractVector{T},
-                            len::Int) where {T<:Real}
+                            len::Int, coeff_func=nothing) where {T<:Real}
 
     stencil_length          = derivative_order + approximation_order - 1 + (derivative_order+approximation_order)%2
     boundary_stencil_length = derivative_order + approximation_order
@@ -62,22 +63,24 @@ function CenteredDifference(derivative_order::Int,
     low_boundary_coefs      = convert(SVector{boundary_point_count},_low_boundary_coefs)
     high_boundary_coefs     = convert(SVector{boundary_point_count},reverse(SVector{boundary_stencil_length, T}[reverse(low_boundary_coefs[i]) for i in 1:boundary_point_count]))
 
+    coefficients            = coeff_func isa Nothing ? nothing : Vector{T}(undef,len)
+
     DerivativeOperator{T,typeof(dx),typeof(stencil_coefs),
-                       typeof(low_boundary_coefs),Nothing,
-                       Nothing}(
+                       typeof(low_boundary_coefs),typeof(coefficients),
+                       typeof(coeff_func)}(
         derivative_order, approximation_order, dx,
         len, stencil_length,
         stencil_coefs,
         boundary_stencil_length,
         boundary_point_count,
         low_boundary_coefs,
-        high_boundary_coefs,nothing,nothing,false
+        high_boundary_coefs,coefficients,coeff_func,false
         )
 end
 
 function UpwindDifference(derivative_order::Int,
                           approximation_order::Int, dx::T,
-                          len::Int, coeff_func) where {T<:Real}
+                          len::Int, coeff_func=nothing) where {T<:Real}
 
     stencil_length          = derivative_order + approximation_order - 1 + (derivative_order+approximation_order)%2
     boundary_stencil_length = derivative_order + approximation_order
@@ -109,7 +112,7 @@ end
 
 function UpwindDifference(derivative_order::Int,
                           approximation_order::Int, dx::AbstractVector{T},
-                          len::Int, coeff_func) where {T<:Real}
+                          len::Int, coeff_func=nothing) where {T<:Real}
 
     stencil_length          = derivative_order + approximation_order - 1 + (derivative_order+approximation_order)%2
     boundary_stencil_length = derivative_order + approximation_order