Value Eval::evaluate(const Position& pos) {
Value v;
+ bool useClassical = false;
// Deciding between classical and NNUE eval (~10 Elo): for high PSQ imbalance we use classical,
// but we switch to NNUE during long shuffling or with high material on the board.
-
- bool classical = false;
-
if ( !useNNUE
|| abs(eg_value(pos.psq_score())) * 5 > (850 + pos.non_pawn_material() / 64) * (5 + pos.rule50_count()))
{
v = Evaluation<NO_TRACE>(pos).value(); // classical
- classical = abs(v) >= 300;
+ useClassical = abs(v) >= 300;
}
// If result of a classical evaluation is much lower than threshold fall back to NNUE
- if (!classical && useNNUE)
+ if (useNNUE && !useClassical)
{
- int scale = 1136
- + 20 * pos.non_pawn_material() / 1024;
-
Value nnue = NNUE::evaluate(pos, true); // NNUE
+ int scale = 1136 + 20 * pos.non_pawn_material() / 1024;
Color stm = pos.side_to_move();
Value optimism = pos.this_thread()->optimism[stm];
+ Value psq = (stm == WHITE ? 1 : -1) * eg_value(pos.psq_score());
+ int complexity = abs(nnue - psq) / 256;
+ optimism *= (1 + complexity);
v = (nnue + optimism) * scale / 1024 - optimism;
if (pos.is_chess960())