Use incremental updates more often

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index d3937823fe5a6176583ac5674891a3d83ae4a79a..710898bc15d5929eed398c4dd120e80cf50b3f6a 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1021,10 +1021,13 @@ Value Eval::evaluate(const Position& pos) {
       v = Evaluation<NO_TRACE>(pos).value();
   else
   {
-      // scale and shift NNUE for compatibility with search and classical evaluation
-      auto  adjusted_NNUE = [&](){ return NNUE::evaluate(pos) * 5 / 4 + Tempo; };
+      // Scale and shift NNUE for compatibility with search and classical evaluation
+      auto  adjusted_NNUE = [&](){
+         int mat = pos.non_pawn_material();
+         return NNUE::evaluate(pos) * (1024 + mat / 32) / 1024 + Tempo;
+      };
 
-      // if there is PSQ imbalance use classical eval, with small probability if it is small
+      // If there is PSQ imbalance use classical eval, with small probability if it is small
       Value psq = Value(abs(eg_value(pos.psq_score())));
       int   r50 = 16 + pos.rule50_count();
       bool  largePsq = psq * 16 > (NNUEThreshold1 + pos.non_pawn_material() / 64) * r50;
@@ -1032,9 +1035,14 @@ Value Eval::evaluate(const Position& pos) {
 
       v = classical ? Evaluation<NO_TRACE>(pos).value() : adjusted_NNUE();
 
-      // if the classical eval is small and imbalance large, use NNUE nevertheless.
+      // If the classical eval is small and imbalance large, use NNUE nevertheless.
+      // For the case of opposite colored bishops, switch to NNUE eval with
+      // small probability if the classical eval is less than the threshold.
       if (   largePsq
-          && abs(v) * 16 < NNUEThreshold2 * r50)
+          && (abs(v) * 16 < NNUEThreshold2 * r50
+          || (   pos.opposite_bishops()
+              && abs(v) * 16 < (NNUEThreshold1 + pos.non_pawn_material() / 64) * r50
+              && !(pos.this_thread()->nodes & 0xB))))
           v = adjusted_NNUE();
   }