--- a/src/SbpOperators/stencil.jl	Fri Jul 02 14:23:33 2021 +0200
+++ b/src/SbpOperators/stencil.jl	Wed Jan 19 14:44:24 2022 +0100
@@ -1,10 +1,10 @@
 export CenteredStencil
 
-struct Stencil{T<:Real,N}
+struct Stencil{T,N}
     range::Tuple{Int,Int}
     weights::NTuple{N,T}
 
-    function Stencil(range::Tuple{Int,Int},weights::NTuple{N,T}) where {T <: Real, N}
+    function Stencil(range::Tuple{Int,Int},weights::NTuple{N,T}) where {T, N}
         @assert range[2]-range[1]+1 == N
         new{T,N}(range,weights)
     end
@@ -15,13 +15,19 @@
 
 Create a stencil with the given weights with element `center` as the center of the stencil.
 """
-function Stencil(weights::Vararg{Number}; center::Int)
+function Stencil(weights::Vararg{T}; center::Int) where T # Type parameter T makes sure the weights are valid for the Stencil constuctors and throws an earlier, more readable, error
     N = length(weights)
     range = (1, N) .- center
 
     return Stencil(range, weights)
 end
 
+function Stencil{T}(s::Stencil) where T
+    return Stencil(s.range, T.(s.weights))
+end
+
+Base.convert(::Type{Stencil{T}}, stencil) where T = Stencil{T}(stencil)
+
 function CenteredStencil(weights::Vararg)
     if iseven(length(weights))
         throw(ArgumentError("a centered stencil must have an odd number of weights."))