Removed quadratic term in optimism

Remove term which is quadratic in optimism in the eval. Simplifies and should also remove the bias towards side to move making the eval better for analysis. STC: https://tests.stockfishchess.org/tests/view/6470a9d8c29e0d4352b0bca5 LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 154432 W: 41127 L: 41040 D: 72265 Ptnml(0-2): 380, 17094, 42190, 17163, 389 LTC: https://tests.stockfishchess.org/tests/view/6471e9b3e549d9cf2fb219ef LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 127926 W: 34474 L: 34369 D: 59083 Ptnml(0-2): 43, 12505, 38776, 12582, 57 closes #4590 Bench: 2541211
official-stockfish · May 28, 2023 · 7e9b131 · 7e9b131
1 parent 7f0b19d
commit 7e9b131
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diff --git a/AUTHORS b/AUTHORS
@@ -213,6 +213,7 @@ tttak
 Unai Corzo (unaiic)
 Uri Blass (uriblass)
 Vince Negri (cuddlestmonkey)
+windfishballad
 xefoci7612
 zz4032
 

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -1072,7 +1072,7 @@ Value Eval::evaluate(const Position& pos) {
 
       // Blend nnue complexity with (semi)classical complexity
       nnueComplexity = (  397 * nnueComplexity
-                        + (477 + optimism) * abs(psq - nnue)
+                        + 477 * abs(psq - nnue)
                         ) / 1024;
 
       optimism += optimism * nnueComplexity / 256;