union rule for Chebyshev and Jacobi (#83)

* union rule for Chebyshev and Jacobi

* incompatible domain cheby-legendre union

* version bump to v0.4.13

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunOrthogonalPolynomials"
 uuid = "b70543e2-c0d9-56b8-a290-0d4d6d4de211"
-version = "0.4.12"
+version = "0.4.13"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/Spaces/Jacobi/JacobiOperators.jl

@@ -487,20 +487,28 @@ end
 
 
 function union_rule(A::Chebyshev,B::Jacobi)
-    if isapprox(B.a,-0.5) && isapprox(B.b,-0.5)
-        # the spaces are the same
-        A
+    if domainscompatible(A, B)
+        if isapprox(B.a,-0.5) && isapprox(B.b,-0.5)
+            # the spaces are the same
+            A
+        else
+            union(Jacobi(A),B)
+        end
     else
-        union(Jacobi(A),B)
+        NoSpace()
     end
 end
 function union_rule(A::Ultraspherical,B::Jacobi)
     m=order(A)
-    if isapprox(B.a,m-0.5) && isapprox(B.b,m-0.5)
-        # the spaces are the same
-        A
+    if domainscompatible(A, B)
+        if isapprox(B.a,m-0.5) && isapprox(B.b,m-0.5)
+            # the spaces are the same
+            A
+        else
+            union(Jacobi(A),B)
+        end
     else
-        union(Jacobi(A),B)
+        NoSpace()
     end
 end
 

test/JacobiTest.jl

@@ -169,6 +169,22 @@ import ApproxFunOrthogonalPolynomials: jacobip
         @test maxspace(a,b) == NoSpace()
         @test union(a,b) == Jacobi(-0.5,-0.5)
         @test !hasconversion(a,b)
+
+        @testset for a in Any[Chebyshev(0..1), Ultraspherical(1, 0..1)]
+            b = ApproxFunBase.setdomain(Jacobi(a), 1..2)
+            c = union(a, b)
+            d = domain(c)
+            @test 0 in d
+            @test 1 in d
+            @test 2 in d
+
+            b = Legendre(1..2)
+            c = union(a, b)
+            d = domain(c)
+            @test 0 in d
+            @test 1 in d
+            @test 2 in d
+        end
     end
 
     @testset "Reverse orientation" begin