From 4e2da3acdf81940bba9f11bf6ee7195a345c4e46 Mon Sep 17 00:00:00 2001
From: Daniel Karrasch <daniel.karrasch@posteo.de>
Date: Sat, 9 Aug 2025 18:36:25 +0200
Subject: [PATCH] Extend 3-arg `dot` to generic `HermOrSym` sparse matrices

---
 src/linalg.jl  | 18 ++++++++++++------
 test/linalg.jl |  5 +++--
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/linalg.jl b/src/linalg.jl
index 9f813246..e3207cd4 100644
--- a/src/linalg.jl
+++ b/src/linalg.jl
@@ -1,7 +1,7 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
 using LinearAlgebra: AbstractTriangular, StridedMaybeAdjOrTransMat, UpperOrLowerTriangular,
-    RealHermSymComplexHerm, checksquare, sym_uplo, wrap
+    RealHermSymComplexHerm, HermOrSym, checksquare, sym_uplo, wrap
 using Random: rand!
 
 const tilebufsize = 10800  # Approximately 32k/3
@@ -1210,6 +1210,9 @@ function nzrangelo(A, i, excl=false)
     @inbounds r2 < r1 || rv[r1] >= i + excl ? r : (searchsortedfirst(view(rv, r1:r2), i + excl) + r1-1):r2
 end
 
+dot(x::AbstractVector, A::HermOrSym{<:Any,<:AbstractSparseMatrixCSC}, y::AbstractVector) =
+    _dot(x, parent(A), y, A.uplo == 'U' ? nzrangeup : nzrangelo, A isa Symmetric ? identity : real, A isa Symmetric ? transpose : adjoint)
+# disambiguation
 dot(x::AbstractVector, A::RealHermSymComplexHerm{<:Real,<:AbstractSparseMatrixCSC}, y::AbstractVector) =
     _dot(x, parent(A), y, A.uplo == 'U' ? nzrangeup : nzrangelo, A isa Symmetric ? identity : real, A isa Symmetric ? transpose : adjoint)
 function _dot(x::AbstractVector, A::AbstractSparseMatrixCSC, y::AbstractVector, rangefun::Function, diagop::Function, odiagop::Function)
@@ -1242,9 +1245,12 @@ function _dot(x::AbstractVector, A::AbstractSparseMatrixCSC, y::AbstractVector,
     end
     return r
 end
-dot(x::SparseVector, A::RealHermSymComplexHerm{<:Real,<:AbstractSparseMatrixCSC}, y::SparseVector) =
-    _dot(x, parent(A), y, A.uplo == 'U' ? nzrangeup : nzrangelo, A isa Symmetric ? identity : real)
-function _dot(x::SparseVector, A::AbstractSparseMatrixCSC, y::SparseVector, rangefun::Function, diagop::Function)
+dot(x::AbstractSparseVector, A::HermOrSym{<:Any,<:AbstractSparseMatrixCSC}, y::AbstractSparseVector) =
+    _dot(x, parent(A), y, A.uplo == 'U' ? nzrangeup : nzrangelo, A isa Symmetric ? identity : real, A isa Symmetric ? transpose : adjoint)
+# disambiguation
+dot(x::AbstractSparseVector, A::RealHermSymComplexHerm{<:Real,<:AbstractSparseMatrixCSC}, y::AbstractSparseVector) =
+    _dot(x, parent(A), y, A.uplo == 'U' ? nzrangeup : nzrangelo, A isa Symmetric ? identity : real, A isa Symmetric ? transpose : adjoint)
+function _dot(x::AbstractSparseVector, A::AbstractSparseMatrixCSC, y::AbstractSparseVector, rangefun::Function, diagop::Function, odiagop::Function)
     m, n = size(A)
     length(x) == m && n == length(y) ||
         throw(DimensionMismatch("x has length $(length(x)), A has size ($m, $n), y has length $(length(y))"))
@@ -1275,7 +1281,7 @@ function _dot(x::SparseVector, A::AbstractSparseMatrixCSC, y::SparseVector, rang
         A_ptr_lo = first(rangefun(A, xi, true))
         A_ptr_hi = last(rangefun(A, xi, true))
         if A_ptr_lo <= A_ptr_hi
-            r += dot(xv, _spdot((a, y) -> a'y, A_ptr_lo, A_ptr_hi, Arowval, Anzval,
+            r += dot(xv, _spdot((a, y) -> odiagop(a)*y, A_ptr_lo, A_ptr_hi, Arowval, Anzval,
                                             1, length(ynzind), ynzind, ynzval))
         end
     end
@@ -2241,7 +2247,7 @@ end
 #         return F
 #     end
 # end
-function factorize(A::LinearAlgebra.RealHermSymComplexHerm{Float64,<:AbstractSparseMatrixCSC})
+function factorize(A::RealHermSymComplexHerm{Float64,<:AbstractSparseMatrixCSC})
     F = cholesky(A; check = false)
     if LinearAlgebra.issuccess(F)
         return F
diff --git a/test/linalg.jl b/test/linalg.jl
index 68ea6809..a48d17b6 100644
--- a/test/linalg.jl
+++ b/test/linalg.jl
@@ -954,12 +954,13 @@ end
         @test dot(x, A, y) ≈ dot(x, Av, y)
     end
 
-    for (T, trans) in ((Float64, Symmetric), (ComplexF64, Symmetric), (ComplexF64, Hermitian)), uplo in (:U, :L)
+    for T in (Float64, ComplexF64, Quaternion{Float64}), trans in (Symmetric,  Hermitian), uplo in (:U, :L)
         B = sprandn(T, 10, 10, 0.2)
         x = sprandn(T, 10, 0.4)
+        xd = Vector(x)
         S = trans(B'B, uplo)
         Sd = trans(Matrix(B'B), uplo)
-        @test dot(x, S, x) ≈ dot(x, Sd, x) ≈ dot(Vector(x), S, Vector(x)) ≈ dot(Vector(x), Sd, Vector(x))
+        @test dot(x, S, x) ≈ dot(x, Sd, x) ≈ dot(xd, S, xd) ≈ dot(xd, Sd, xd)
     end
 end