Simplify away nnue scale pawn count multiplier

Removes 2x multipliers in nnue scale calculation along with the pawn count term that was recently reintroduced.

Passed non-regression STC:
https://tests.stockfishchess.org/tests/view/64305bc720eb941419bdf72e
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 38008 W: 10234 L: 10021 D: 17753
Ptnml(0-2): 96, 4151, 10323, 4312, 122

Passed non-regression LTC:
https://tests.stockfishchess.org/tests/view/6430b76a028b029b01ac9bfd
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 91232 W: 24686 L: 24547 D: 41999
Ptnml(0-2): 30, 8721, 27986, 8838, 41

closes https://github.com/official-stockfish/Stockfish/pull/4510

bench 4017320

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 2d0df89c3e77f9d692e285cd5ec219b6619d6bf1..873dc5d20693956bea19b72f07acc764a2c14008 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1063,7 +1063,7 @@ Value Eval::evaluate(const Position& pos, int* complexity) {
   else
   {
       int nnueComplexity;
-      int scale = 1001 + 5 * pos.count<PAWN>() + 61 * pos.non_pawn_material() / 4096;
+      int scale = 1001 + pos.non_pawn_material() / 64;
 
       Color stm = pos.side_to_move();
       Value optimism = pos.this_thread()->optimism[stm];