From 9c3a3011a889a0a3b77b08f7a87d57ff13d73ba0 Mon Sep 17 00:00:00 2001
From: David Widmann <devmotion@users.noreply.github.com>
Date: Fri, 10 Nov 2023 09:04:53 +0100
Subject: [PATCH] Ensure that `Matrix` constructor returns a `Matrix` for a
 `PDMat` (#196)

* Ensure that `Matrix` constructor returns a `Matrix` for a `PDMat`

* Add test for `Matrix` constructor

* Check type of `Matrix` for static pd matrices
---
 src/pdmat.jl          | 2 +-
 test/specialarrays.jl | 2 ++
 test/testutils.jl     | 5 +++++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/pdmat.jl b/src/pdmat.jl
index bc09e3e..0e44780 100644
--- a/src/pdmat.jl
+++ b/src/pdmat.jl
@@ -42,7 +42,7 @@ Base.convert(::Type{AbstractPDMat{T}}, a::PDMat) where {T<:Real} = convert(PDMat
 ### Basics
 
 Base.size(a::PDMat) = (a.dim, a.dim)
-Base.Matrix(a::PDMat) = copy(a.mat)
+Base.Matrix(a::PDMat) = Matrix(a.mat)
 LinearAlgebra.diag(a::PDMat) = diag(a.mat)
 LinearAlgebra.cholesky(a::PDMat) = a.chol
 
diff --git a/test/specialarrays.jl b/test/specialarrays.jl
index e896d72..75468ba 100644
--- a/test/specialarrays.jl
+++ b/test/specialarrays.jl
@@ -28,6 +28,8 @@ using StaticArrays
         Y = @SMatrix rand(4, 10)
 
         for A in (PDS, D, E, C)
+            @test Matrix(A) isa Matrix
+
             if !(A isa Cholesky)
                 # `*(::Cholesky, ::SArray)` is not defined
                 @test A * x isa SVector{4, Float64}
diff --git a/test/testutils.jl b/test/testutils.jl
index 96843c9..32bd5a9 100644
--- a/test/testutils.jl
+++ b/test/testutils.jl
@@ -98,6 +98,11 @@ function pdtest_basics(C, Cmat::Matrix, d::Int, verbose::Int)
     if C isa AbstractPDMat
         @test M === C
     end
+
+    _pdt(verbose, "Matrix")
+    M = Matrix(C)
+    @test M isa Matrix
+    @test M == Cmat
 end