From 04c1aecc80e6523fe67ca93c30ea5ef12492fd10 Mon Sep 17 00:00:00 2001
From: Frames Catherine White <oxinabox@ucc.asn.au>
Date: Tue, 12 Apr 2022 07:08:31 +0200
Subject: [PATCH] use ProjectTo in rules for constructors of triangular
 matrixes

---
 src/rulesets/LinearAlgebra/structured.jl | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/rulesets/LinearAlgebra/structured.jl b/src/rulesets/LinearAlgebra/structured.jl
index 1a5a4bcd0..b50ec08eb 100644
--- a/src/rulesets/LinearAlgebra/structured.jl
+++ b/src/rulesets/LinearAlgebra/structured.jl
@@ -208,15 +208,17 @@ end
 #####
 
 function rrule(::Type{<:UpperTriangular}, A::AbstractMatrix)
+    project = ProjectTo(A)
     function UpperTriangular_pullback(ȳ)
-        return (NoTangent(), Matrix(ȳ))
+        return (NoTangent(), project(ȳ))
     end
     return UpperTriangular(A), UpperTriangular_pullback
 end
 
 function rrule(::Type{<:LowerTriangular}, A::AbstractMatrix)
+    project = ProjectTo(A)
     function LowerTriangular_pullback(ȳ)
-        return (NoTangent(), Matrix(ȳ))
+        return (NoTangent(), project(ȳ))
     end
     return LowerTriangular(A), LowerTriangular_pullback
 end