Update WLD model

using data of May, recalibrate the WLD model.

closes https://github.com/official-stockfish/Stockfish/pull/4577

No functional change

diff --git a/src/uci.cpp b/src/uci.cpp
index 8f9684ee26566ea9a00e5278803b32b8eca1d44b..523d551e0c051cee5578e951bb70cce4d553e0e0 100644 (file)
--- a/src/uci.cpp
+++ b/src/uci.cpp
@@ -207,8 +207,8 @@ 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[] = {   0.33677609,   -4.30175627,   33.08810557,  365.60223431};
-     constexpr double bs[] = {  -2.50471102,   14.23235405,  -14.33066859,   71.42705250 };
+     constexpr double as[] = {   1.07390458,   -6.94334517,   31.95090161,  317.75424048};
+     constexpr double bs[] = {  -2.82843814,   16.64518180,  -19.74439200,   68.39499088 };
 
      // 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 9ca0ed36b4dd0385609f4d7dd317b70cc2f97eb9..680d2d2cc8cff535c435289dbb60322eded1e6f7 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 = 394;
+const int NormalizeToPawnValue = 343;
 
 class Option;