From 6408cb77690f32195479f2053f9705d91dc6492a Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Fri, 26 Jul 2024 15:05:52 +0530
Subject: [PATCH] Separate parent matrix type from Cholesky parameter

---
 src/pdmat.jl     | 8 ++++----
 test/pdmtypes.jl | 5 +++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/pdmat.jl b/src/pdmat.jl
index 7f4fcf0..f961545 100644
--- a/src/pdmat.jl
+++ b/src/pdmat.jl
@@ -1,11 +1,11 @@
 """
 Full positive definite matrix together with a Cholesky factorization object.
 """
-struct PDMat{T<:Real,S<:AbstractMatrix} <: AbstractPDMat{T}
-    mat::S
+struct PDMat{T<:Real,S<:AbstractMatrix{T},M<:AbstractMatrix{T}} <: AbstractPDMat{T}
+    mat::M
     chol::Cholesky{T,S}
 
-    PDMat{T,S}(m::AbstractMatrix{T},c::Cholesky{T,S}) where {T,S} = new{T,S}(m,c)
+    PDMat{T,S}(m::M, c::Cholesky{T,S}) where {T,S<:AbstractMatrix{T},M<:AbstractMatrix{T}} = new{T,S,M}(m,c)
 end
 
 function PDMat(mat::AbstractMatrix,chol::Cholesky{T,S}) where {T,S}
@@ -13,7 +13,7 @@ function PDMat(mat::AbstractMatrix,chol::Cholesky{T,S}) where {T,S}
     if size(chol, 1) != d
         throw(DimensionMismatch("Dimensions of mat and chol are inconsistent."))
     end
-    PDMat{T,S}(convert(S, mat), chol)
+    PDMat{T,S}(convert(AbstractMatrix{T}, mat), chol)
 end
 
 PDMat(mat::AbstractMatrix) = PDMat(mat, cholesky(mat))
diff --git a/test/pdmtypes.jl b/test/pdmtypes.jl
index a8f7530..f5b640d 100644
--- a/test/pdmtypes.jl
+++ b/test/pdmtypes.jl
@@ -164,6 +164,11 @@ using Test
         end
     end
 
+    @testset "PDMat fro SymTridiagonal" begin
+        S = SymTridiagonal(fill(4,4), fill(1,3))
+        @test PDMat(S) == S
+    end
+
     @testset "AbstractPDMat constructors (#136)" begin
         x = rand(10, 10)
         A = Array(Symmetric(x' * x + I))