Fix BandedMatrices #188 (#29)

Author: dlfivefifty

Project.toml

@@ -1,7 +1,7 @@
 name = "ArrayLayouts"
 uuid = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
 authors = ["Sheehan Olver <[email protected]>"]
-version = "0.3.6"
+version = "0.3.7"
 
 [deps]
 FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"

src/diagonal.jl

@@ -27,6 +27,11 @@ end
 copy(M::Rmul{<:Any,<:DiagonalLayout}) = M.A .* permutedims(M.B.diag)
 copy(M::Rmul{<:Any,<:DiagonalLayout{<:AbstractFillLayout}}) =  M.A .* getindex_value(M.B.diag)
 
+function materialize!(M::Ldiv{<:DiagonalLayout})
+    M.B .= M.A.diag .\ M.B
+    M.B
+end
+
 copy(M::Ldiv{<:DiagonalLayout,<:DiagonalLayout}) = Diagonal(inv.(M.A.diag) .* M.B.diag)
 copy(M::Ldiv{<:DiagonalLayout}) = inv.(M.A.diag) .* M.B
 copy(M::Ldiv{<:DiagonalLayout{<:AbstractFillLayout}}) = inv(getindex_value(M.A.diag)) .* M.B

src/triangular.jl

@@ -116,7 +116,7 @@ materialize!(M::MatRmulMat{<:AbstractStridedLayout,<:TriangularLayout}) = Linear
 ########
 
 
-@inline function copyto!(dest::AbstractArray, M::Ldiv{<:Union{TriangularLayout,BidiagonalLayout}})
+@inline function copyto!(dest::AbstractArray, M::Ldiv{<:Union{TriangularLayout,BidiagonalLayout,DiagonalLayout}})
     A, B = M.A, M.B
     dest ≡ B || copyto!(dest, B)
     ldiv!(A, dest)

test/test_ldiv.jl

@@ -249,5 +249,15 @@ import ArrayLayouts: ApplyBroadcastStyle, QRCompactWYQLayout, QRCompactWYLayout,
         @test_throws DimensionMismatch ArrayLayouts.ldiv(L,randn(3))
         @test_throws DimensionMismatch materialize!(Ldiv(L,randn(3)))
     end
+
+    @testset "Diagonal Ldiv bug (BandedMatrices #188)" begin
+        n = 5
+        B = randn(n,n)
+        D = Diagonal(-collect(1.0:n))
+        @test ArrayLayouts.ldiv!(similar(B), D, B) == D \ B
+        @test ArrayLayouts.ldiv!(similar(B), B, D) == B \ D
+        @test ArrayLayouts.rdiv!(similar(B), B, D) ==  B / D
+        @test_broken ArrayLayouts.rdiv!(similar(B), D, B) ==  D / B
+    end
 end