Infer domainspace in Jacobi Multiplication (#85)

* Infer domainspace in Jacobi Multiplication

* Add test

Author: jishnub

src/JacobiWeight.jl

@@ -423,12 +423,12 @@ function Multiplication(f::Fun{<:JacobiWeight{<:ConstantSpace,<:IntervalOrSegmen
         # decrement β and multiply again
         M1 = ConcreteMultiplication(f.coefficients[1]*jacobiweight(1,0,d),S)
         M1_out = Multiplication(jacobiweight(Sf.β-1,Sf.α,d), rangespace(M1)) * M1
-        MultiplicationWrapper(f, M1_out)
+        MultiplicationWrapper(f, M1_out, S)
     elseif isapproxinteger(Sf.α) && Sf.α ≥ 1 && S.a >0
         # decrement α and multiply again
         M2 = ConcreteMultiplication(f.coefficients[1]*jacobiweight(0,1,d),S)
         M2_out = Multiplication(jacobiweight(Sf.β,Sf.α-1,d), rangespace(M2)) * M2
-        MultiplicationWrapper(f, M2_out)
+        MultiplicationWrapper(f, M2_out, S)
     else
         # default JacobiWeight
         M = Multiplication(Fun(Sf.space, f.coefficients), S)

test/runtests.jl

@@ -108,6 +108,10 @@ end
         g = Fun(x->√(1-x^2), JacobiWeight(0.5, 0.5, Jacobi(1,1)))
         xg = Fun(x->x*√(1-x^2), JacobiWeight(0.5, 0.5, Jacobi(1,1)))
         @test Multiplication(g) * Fun(NormalizedLegendre()) ≈ xg
+
+        f = Fun(x -> (1-x)^2, JacobiWeight(3,4,ConstantSpace(ChebyshevInterval())));
+        S = @inferred (f -> domainspace(Multiplication(f, Jacobi(1,1))))(f)
+        @test S == Jacobi(1,1)
     end
 
     @testset "Derivative" begin
@@ -134,8 +138,7 @@ end
 
     @testset "differentiate" begin
         f = Fun(x -> √(1-x^2) * x^2, JacobiWeight(0.5, 0.5, Chebyshev()))
-        df(f) = 
-ApproxFunSingularities.differentiate(f)
+        df(f) = ApproxFunSingularities.differentiate(f)
         g = if VERSION >= v"1.9"
                 @inferred df(f)
             else