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
This commit is contained in:
Robert Nurnberg @ elitebook
2026-01-15 22:19:50 +01:00
committed by Joost VandeVondele
parent 5b8b304ebd
commit 71f53b92c7
+2 -2
View File
@@ -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];