Fix convert for ConcreteOperatorFunction (#250)

* Fix convert for ConcreteOperatorFunction

* compute output eltype from input

* Add conversion test

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunBase"
 uuid = "fbd15aa5-315a-5a7d-a8a4-24992e37be05"
-version = "0.7.27"
+version = "0.7.28"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/Operators/general/OperatorFunction.jl

@@ -8,8 +8,10 @@ struct ConcreteOperatorFunction{BT<:Operator,FF,T} <: OperatorFunction{BT,FF,T}
     f::FF
 end
 
-ConcreteOperatorFunction(op::Operator,f::Function) =
-    ConcreteOperatorFunction{typeof(op),typeof(f),eltype(op)}(op,f)
+function ConcreteOperatorFunction(op::Operator,f::Function)
+    T = typeof(f(oneunit(eltype(op))))
+    ConcreteOperatorFunction{typeof(op),typeof(f),T}(op,f)
+end
 OperatorFunction(op::Operator,f::Function) = ConcreteOperatorFunction(op,f)
 
 for op in (:domainspace,:rangespace,:domain,:bandwidths)
@@ -31,7 +33,8 @@ function convert(::Type{Operator{T}},D::ConcreteOperatorFunction) where T
     if T==eltype(D)
         D
     else
-        ConcreteOperatorFunction{typeof(D.op),T}(D.op,D.f)
+        DopT = strictconvert(Operator{T}, D.op)
+        ConcreteOperatorFunction(DopT, D.f)::Operator{T}
     end
 end
 

test/SpacesTest.jl

@@ -171,6 +171,14 @@ using LinearAlgebra
             P = PartialInverseOperator(C)
             @test AbstractMatrix(P * C) == I(size(C,1))
         end
+
+        @testset "ConcreteOperatorFunction" begin
+            A = 2I : PointSpace(1:4)
+            Ainv = inv(A)
+            B = convert(Operator{ComplexF64}, Ainv)
+            @test B isa Operator{ComplexF64}
+            @test ComplexF64.(Ainv[1:4, 1:4]) == B[1:4, 1:4]
+        end
     end
 
     @testset "DiracSpace" begin