fix arg order

Author: dlfivefifty

src/rect.jl

@@ -62,22 +62,22 @@ function weaklaplacian(P::RectPolynomial)
     A,B = P.args
     Δ_A,Δ_B = weaklaplacian(A), weaklaplacian(B)
     M_A,M_B = grammatrix(A), grammatrix(B)
-    KronTrav(Δ_A,M_B) + KronTrav(M_A,Δ_B)
+    KronTrav(M_B,Δ_A) + KronTrav(Δ_B,M_A)
 end
 
 function \(P::RectPolynomial, Q::RectPolynomial)
     PA,PB = P.args
     QA,QB = Q.args
-    krontrav(PA\QA, PB\QB)
+    krontrav(PB\QB, PA\QA)
 end
 
 @simplify function *(Ac::QuasiAdjoint{<:Any,<:RectPolynomial}, B::RectPolynomial)
     PA,PB = Ac'.args
     QA,QB = B.args
-    KronTrav(PA'QA, PB'QB)
+    KronTrav(PB'QB, PA'QA)
 end
 
-grammatrix(P::KronPolynomial) = KronTrav(grammatrix.(P.args)...)
+grammatrix(P::KronPolynomial) = KronTrav(reverse(grammatrix.(P.args))...)
 
 
 struct ApplyPlan{T, F, Pl}
@@ -104,10 +104,8 @@ function *(A::TensorPlan, B::AbstractArray)
     B
 end
 
-function checkpoints(P::RectPolynomial)
-    x,y = checkpoints.(P.args)
-    SVector.(x, y')
-end
+checkpoints(P::ProductDomain) = tensorgrid(checkpoints.(components(P))...)
+tensorgrid(x,y) = SVector.(x, y')
 
 function plan_transform(P::KronPolynomial{d,<:Any,<:Fill}, B::Tuple{Block{1}}, dims=1:1) where d
     @assert dims == 1

test/test_rect.jl

@@ -61,6 +61,16 @@ using Base: oneto
         @test (Y * (TU \ f))[KR] ≈ (TU \ h)[KR]
     end
 
+    @testset "gram matrix" begin
+        P = Legendre()
+        Q = Ultraspherical(3/2)
+        PQ = RectPolynomial(P, Q)
+        M = grammatrix(PQ)
+        f = expand(PQ, splat((x,y) -> exp(x*cos(y + 1))))
+        g = expand(PQ, splat((x,y) -> sin(x*cos(y + 1)+2)))
+        @test coefficients(g)[1:100]'M[1:100,1:100] * coefficients(f)[1:100] ≈ sum(expand(T², 𝐱 -> f[𝐱]g[𝐱]))
+    end
+
     @testset "Conversion" begin
         T = ChebyshevT()
         U = ChebyshevU()