From 71f53b92c7095f1f145b85d63b8ad49f9ef553f9 Mon Sep 17 00:00:00 2001
From: "Robert Nurnberg @ elitebook" <robert.nurnberg@gmx.de>
Date: Thu, 15 Jan 2026 09:01:18 +0100
Subject: [PATCH] update the WDL model

This PR updates the internal WDL model, using data from 3.1M games played by
the revisions since 44d5467. Note that the normalizing constant increases only
moderately from 377 to 385.

closes https://github.com/official-stockfish/Stockfish/pull/6549

No functional change
---
 src/uci.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/uci.cpp b/src/uci.cpp
index 139d97b60..927007686 100644
--- a/src/uci.cpp
+++ b/src/uci.cpp
@@ -507,8 +507,8 @@ WinRateParams win_rate_params(const Position& pos) {
     double m = std::clamp(material, 17, 78) / 58.0;
 
     // Return a = p_a(material) and b = p_b(material), see github.com/official-stockfish/WDL_model
-    constexpr double as[] = {-13.50030198, 40.92780883, -36.82753545, 386.83004070};
-    constexpr double bs[] = {96.53354896, -165.79058388, 90.89679019, 49.29561889};
+    constexpr double as[] = {-72.32565836, 185.93832038, -144.58862193, 416.44950446};
+    constexpr double bs[] = {83.86794042, -136.06112997, 69.98820887, 47.62901433};
 
     double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];
     double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];