Update WLD model

update the WLD model with about 400M positions extracted from recent LTC games after the net updates.
This ensures that the 50% win rate is again at 1.0 eval.

closes https://github.com/official-stockfish/Stockfish/pull/4373

No functional change.

diff --git a/src/uci.cpp b/src/uci.cpp
index 2afd2de730049b5fd018eda7a52fc789da4ecb79..3883b3d370769a9d6469a7fef9b3842f71871c64 100644 (file)
--- a/src/uci.cpp
+++ b/src/uci.cpp
@@ -206,8 +206,8 @@ namespace {
      // The coefficients of a third-order polynomial fit is based on the fishtest data
      // for two parameters that need to transform eval to the argument of a logistic
      // function.
-     constexpr double as[] = {  -0.58270499,    2.68512549,   15.24638015,  344.49745382};
-     constexpr double bs[] = {  -2.65734562,   15.96509799,  -20.69040836,   73.61029937 };
+     constexpr double as[] = {   0.33677609,   -4.30175627,   33.08810557,  365.60223431};
+     constexpr double bs[] = {  -2.50471102,   14.23235405,  -14.33066859,   71.42705250 };
 
      // Enforce that NormalizeToPawnValue corresponds to a 50% win rate at ply 64
      static_assert(UCI::NormalizeToPawnValue == int(as[0] + as[1] + as[2] + as[3]));

diff --git a/src/uci.h b/src/uci.h
index bd3df323f0a0d069102da573376979c0c9da3b7a..5d8ccf1afff99e759f30e1eef9fa6c7742be9053 100644 (file)
--- a/src/uci.h
+++ b/src/uci.h
@@ -35,7 +35,7 @@ namespace UCI {
 // the win_rate_model() such that Stockfish outputs an advantage of
 // "100 centipawns" for a position if the engine has a 50% probability to win
 // from this position in selfplay at fishtest LTC time control.
-const int NormalizeToPawnValue = 361;
+const int NormalizeToPawnValue = 394;
 
 class Option;