Non-linear bonus for pawn count

[stockfish] / src / material.cpp

diff --git a/src/material.cpp b/src/material.cpp
index 64a5bff033f9e7579fa33c9c94c3ea3f9dec0b22..d98eb125e4bb5f84c8ebda36b1d146b20f5fdb41 100644 (file)
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -34,11 +34,11 @@ namespace {
   constexpr int QuadraticOurs[][PIECE_TYPE_NB] = {
     //            OUR PIECES
     // pair pawn knight bishop rook queen
-    {1667                               }, // Bishop pair
+    {1443                               }, // Bishop pair
     {  40,    0                         }, // Pawn
-    {  32,  255,  -3                    }, // Knight      OUR PIECES
+    {  32,  255, -67                    }, // Knight      OUR PIECES
     {   0,  104,   4,    0              }, // Bishop
-    { -26,   -2,  47,   105,  -149      }, // Rook
+    { -26,   -2,  47,   105,  -221      }, // Rook
     {-189,   24, 117,   133,  -134, -10 }  // Queen
   };
 
@@ -53,6 +53,8 @@ namespace {
     {  97,  100, -42,   137,  268,    0 }  // Queen
   };
 
+  constexpr int PawnCount[] = { 0, 304,  144, -320, -560, -704, -672, -464, -320 };
+
   // Endgame evaluation and scaling functions are accessed directly and not through
   // the function maps because they correspond to more than one material hash key.
   Endgame<KXK>    EvaluateKXK[] = { Endgame<KXK>(WHITE),    Endgame<KXK>(BLACK) };
@@ -89,7 +91,7 @@ namespace {
 
     constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
 
-    int bonus = 0;
+    int bonus = PawnCount[pieceCount[Us][PAWN]];
 
     // Second-degree polynomial material imbalance, by Tord Romstad
     for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)