From 87302527a9c28ce7ebd77a0494ec12f5178fdece Mon Sep 17 00:00:00 2001
From: Alexis Montoison <35051714+amontoison@users.noreply.github.com>
Date: Tue, 5 Nov 2024 16:16:45 -0600
Subject: [PATCH] Remove broadcast in MINRES-QLP

---
 src/minres_qlp.jl | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/minres_qlp.jl b/src/minres_qlp.jl
index 2538a1802..5c70ddcc9 100644
--- a/src/minres_qlp.jl
+++ b/src/minres_qlp.jl
@@ -353,8 +353,11 @@ kwargs_minres_qlp = (:M, :ldiv, :λ, :atol, :rtol, :Artol, :itmax, :timemax, :ve
         # [w̅ₖ₋₁ vₖ] [cpₖ  spₖ] = [ẘₖ₋₁ w̅ₖ] ⟷ ẘₖ₋₁ = cpₖ * w̅ₖ₋₁ + spₖ * vₖ
         #           [spₖ -cpₖ]             ⟷ w̅ₖ   = spₖ * w̅ₖ₋₁ - cpₖ * vₖ
         @kswap!(wₖ₋₁, wₖ)
-        wₖ .= spₖ .* wₖ₋₁ .- cpₖ .* vₖ
-        kaxpby!(n, spₖ, vₖ, cpₖ, wₖ₋₁)
+        # Compute w̅ₖ
+        kcopy!(n, wₖ, wₖ₋₁)
+        kaxpby!(n, spₖ, vₖ, cpₖ, wₖ)
+        # Compute ẘₖ₋₁
+        kaxpby!(n, -cpₖ, vₖ, spₖ, wₖ₋₁)
       else
         # [ẘₖ₋₂ w̄ₖ₋₁ vₖ] [cpₖ  0   spₖ] [1   0    0 ] = [wₖ₋₂ ẘₖ₋₁ w̄ₖ] ⟷ wₖ₋₂ = cpₖ * ẘₖ₋₂ + spₖ * vₖ
         #                [ 0   1    0 ] [0  cdₖ  sdₖ]                  ⟷ ẘₖ₋₁ = cdₖ * w̄ₖ₋₁ + sdₖ * (spₖ * ẘₖ₋₂ - cpₖ * vₖ)