Public function to access the uplo for Symmetric/Hermitian

Author: jishnub

src/LinearAlgebra.jl

@@ -181,7 +181,8 @@ public AbstractTriangular,
         zeroslike,
         matprod_dest,
         fillstored!,
-        fillband!
+        fillband!,
+        uplo
 
 const BlasFloat = Union{Float64,Float32,ComplexF64,ComplexF32}
 const BlasReal = Union{Float64,Float32}

src/symmetric.jl

@@ -237,6 +237,33 @@ nonhermitianwrappertype(::SymSymTri{<:Real}) = Symmetric
 nonhermitianwrappertype(::Hermitian{<:Real}) = Symmetric
 nonhermitianwrappertype(::Hermitian) = identity
 
+"""
+    LinearAlgebra.uplo(S::Union{Symmetric, Hermitian})::Char
+
+Return a `Char` corresponding to the stored triangular half in the matrix `S`,
+that is, the elements are common between `S` and `parent(S)` for that triangular half.
+
+# Example
+```jldoctest
+julia> S = Symmetric([1 2; 3 4])
+2×2 Symmetric{Int64, Matrix{Int64}}:
+ 1  2
+ 2  4
+
+julia> LinearAlgebra.uplo(S)
+'U': ASCII/Unicode U+0055 (category Lu: Letter, uppercase)
+
+julia> H = Hermitian([1 2; 3 4], :L)
+2×2 Hermitian{Int64, Matrix{Int64}}:
+ 1  3
+ 3  4
+
+julia> LinearAlgebra.uplo(H)
+'L': ASCII/Unicode U+004C (category Lu: Letter, uppercase)
+```
+"""
+uplo(S::HermOrSym) = S.uplo
+
 size(A::HermOrSym) = size(A.data)
 axes(A::HermOrSym) = axes(A.data)
 @inline function Base.isassigned(A::HermOrSym, i::Int, j::Int)