Remove optimism multiplier in nnue eval calculation

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 851ccfe11c940efc633a722f46262f696763b136..35d054270ee7120e1f0438f58867248146053edc 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1063,20 +1063,16 @@ Value Eval::evaluate(const Position& pos) {
   else
   {
       int nnueComplexity;
-      int scale = 1001 + pos.non_pawn_material() / 64;
+      int npm = pos.non_pawn_material() / 64;
 
       Color stm = pos.side_to_move();
       Value optimism = pos.this_thread()->optimism[stm];
 
       Value nnue = NNUE::evaluate(pos, true, &nnueComplexity);
 
-      // Blend nnue complexity with (semi)classical complexity
-      nnueComplexity = (  406 * nnueComplexity
-                        + (424 + optimism) * abs(psq - nnue)
-                        ) / 1024;
-
-      optimism = optimism * (272 + nnueComplexity) / 256;
-      v = (nnue * scale + optimism * (scale - 748)) / 1024;
+      // Blend optimism with nnue complexity and (semi)classical complexity
+      optimism += optimism * (nnueComplexity + abs(psq - nnue)) / 512;
+      v = (nnue * (945 + npm) + optimism * (150 + npm)) / 1024;
   }
 
   // Damp down the evaluation linearly when shuffling