From ad4af83ec549f78098ef770b611eb6961245367f Mon Sep 17 00:00:00 2001
From: Sheehan Olver <solver@mac.com>
Date: Wed, 27 Nov 2024 15:23:20 +0000
Subject: [PATCH] overload simplifiable for special cases of Mul (#188)

* overload simplifiable for special cases of Mul

* increase codecov
---
 Project.toml            |  2 +-
 src/banded/infbanded.jl |  3 +++
 test/test_infbanded.jl  | 16 ++++++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 7d88418..6f939df 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "InfiniteLinearAlgebra"
 uuid = "cde9dba0-b1de-11e9-2c62-0bab9446c55c"
-version = "0.8.4"
+version = "0.8.5"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
diff --git a/src/banded/infbanded.jl b/src/banded/infbanded.jl
index 215104a..67121ce 100644
--- a/src/banded/infbanded.jl
+++ b/src/banded/infbanded.jl
@@ -428,6 +428,7 @@ similar(M::MulAdd{<:AbstractBandedLayout,<:AbstractBandedLayout}, ::Type{T}, axe
 # BandedFill * BandedFill
 ###
 
+simplifiable(::Mul{<:BandedColumns{<:AbstractFillLayout},<:BandedColumns{<:AbstractFillLayout}}) = Val(true)
 copy(M::MulAdd{<:BandedColumns{<:AbstractFillLayout},<:BandedColumns{<:AbstractFillLayout},ZerosLayout}) =
     _bandedfill_mul(M, axes(M.A), axes(M.B))
 
@@ -456,6 +457,8 @@ mulreduce(M::Mul{<:InfToeplitzLayouts}) = ApplyArray(M)
 mulreduce(M::Mul{<:InfToeplitzLayouts,<:PaddedColumns}) = MulAdd(M)
 mulreduce(M::Mul{<:Any, <:InfToeplitzLayouts}) = ApplyArray(M)
 mulreduce(M::Mul{<:AbstractQLayout, <:InfToeplitzLayouts}) = ApplyArray(M)
+simplifiable(::Mul{<:DiagonalLayout, <:InfToeplitzLayouts}) = Val(true)
+simplifiable(::Mul{<:InfToeplitzLayouts, <:DiagonalLayout}) = Val(true)
 mulreduce(M::Mul{<:DiagonalLayout, <:InfToeplitzLayouts}) = Lmul(M)
 mulreduce(M::Mul{<:InfToeplitzLayouts, <:DiagonalLayout}) = Rmul(M)
 
diff --git a/test/test_infbanded.jl b/test/test_infbanded.jl
index 804e17e..5a383e0 100644
--- a/test/test_infbanded.jl
+++ b/test/test_infbanded.jl
@@ -2,6 +2,7 @@ using InfiniteLinearAlgebra, ArrayLayouts, InfiniteArrays, BandedMatrices, FillA
 import BandedMatrices: _BandedMatrix, bandeddata
 using InfiniteLinearAlgebra: InfToeplitz, ConstRows, BandedToeplitzLayout, TridiagonalToeplitzLayout, BidiagonalToeplitzLayout, PertToeplitz, PertToeplitzLayout
 using Base: oneto
+using LazyArrays: simplifiable
 
 @testset "∞-banded" begin
     @testset "Diagonal and BandedMatrix" begin
@@ -55,6 +56,9 @@ using Base: oneto
         @test A * [1; 2; Zeros(∞)] isa Vcat
         @test A * [1; 2; Zeros(∞)] == [A[1:5,1:2] * [1,2]; Zeros(∞)]
 
+        @test A * Vcat([1 2; 3 4], Zeros(∞,2)) isa ApplyMatrix{ComplexF64,typeof(Base.setindex)}
+        @test simplifiable(*, A, Vcat([1 2; 3 4], Zeros(∞,2))) == Val(true)
+
         @test MemoryLayout(Tridiagonal(Fill(1,∞), Fill(2,∞), Fill(3,∞))) isa TridiagonalToeplitzLayout
         @test MemoryLayout(Bidiagonal(Fill(1,∞), Fill(2,∞), :U)) isa BidiagonalToeplitzLayout
         @test MemoryLayout(SymTridiagonal(Fill(1,∞), Fill(2,∞))) isa TridiagonalToeplitzLayout
@@ -87,6 +91,18 @@ using Base: oneto
             @test (B*B)[1:10,1:10] ≈ B[1:10,1:14]B[1:14,1:10]
             @test (A*B)[1:10,1:10] ≈ A[1:10,1:14]B[1:14,1:10]
             @test (B*A)[1:10,1:10] ≈ B[1:10,1:14]A[1:14,1:10]
+            @test simplifiable(*, B, B) == Val(true)
+            @test length((A*B*B).args) == 2
+            @test length((B*B*A).args) == 2
+        end
+
+        @testset "Toep * Diag" begin
+            A = BandedMatrix(1 => Fill(2im,∞), 2 => Fill(-1,∞), 3 => Fill(2,∞), -2 => Fill(-4,∞), -3 => Fill(-2im,∞))
+            D = Diagonal(1:∞)
+            @test D*A isa BroadcastMatrix
+            @test A*D isa BroadcastMatrix
+            @test simplifiable(*, D, A) == Val(true)
+            @test simplifiable(*, A, D) == Val(true)
         end
     end