From 02f2d79887238d51bbd2dbe236a5f3eae4f6d759 Mon Sep 17 00:00:00 2001
From: Sheehan Olver <solver@mac.com>
Date: Tue, 22 Aug 2023 13:24:09 +0100
Subject: [PATCH] =?UTF-8?q?Support=20copymutable=20dispatching=20on=20size?=
 =?UTF-8?q?,=20used=20in=20InfiniteLinearAlgebr=E2=80=A6=20(#53)?=
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* Support copymutable dispatching on size, used in InfiniteLinearAlgebra.jl

* Update MatrixFactorizations.jl

* Update runtests.jl
---
 Project.toml                | 2 +-
 src/MatrixFactorizations.jl | 3 +++
 test/runtests.jl            | 8 ++++++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index e1153b0..1872b6a 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "MatrixFactorizations"
 uuid = "a3b82374-2e81-5b9e-98ce-41277c0e4c87"
-version = "2.0.1"
+version = "2.1"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
diff --git a/src/MatrixFactorizations.jl b/src/MatrixFactorizations.jl
index c073e5d..f80360a 100644
--- a/src/MatrixFactorizations.jl
+++ b/src/MatrixFactorizations.jl
@@ -50,6 +50,9 @@ abstract type LayoutQ{T} <: AbstractQ{T} end
 @_layoutrmul LayoutQ
 @_layoutrmul AdjointQtype{<:Any,<:LayoutQ}
 
+LinearAlgebra.copymutable(Q::LayoutQ) = copymutable_size(size(Q), Q)
+copymutable_size(sz, Q) = lmul!(Q, Matrix{eltype(Q)}(I, sz))
+
 (*)(Q::LayoutQ, b::AbstractVector) = _mul(Q, b)
 (*)(Q::LayoutQ, b::LayoutVector) = ArrayLayouts.mul(Q, b) # disambiguation w/ ArrayLayouts.jl
 function _mul(Q::LayoutQ, b::AbstractVector)
diff --git a/test/runtests.jl b/test/runtests.jl
index 77d1c66..7927a5d 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -436,6 +436,14 @@ end
         @test Q' * LowerTriangular(L) ≈ Q' * L
         @test LowerTriangular(L)' * Q' ≈ A'
     end
+
+    @testset "row/col slices via copymutable" begin
+        n = 5
+        A = randn(n,n)
+        Q, L = ql(A)
+        @test Q[2,3:4] == [Q[2,k] for k=3:4]
+        @test Q[3:4,2] == [Q[k,2] for k=3:4]
+    end
 end
 
 include("test_rq.jl")