Color stm = pos.side_to_move();
Value psq = pos.psq_eg_stm();
- // Deciding between classical and NNUE eval: for high PSQ imbalance we use classical,
- // but we switch to NNUE during long shuffling or with high material on the board.
- bool useClassical = !useNNUE ||
- ((pos.count<ALL_PIECES>() > 7)
- && abs(psq) * 5 > (856 + pos.non_pawn_material() / 64) * (10 + pos.rule50_count()));
-
+ // We use the much less accurate but faster Classical eval when the NNUE
+ // option is set to false. Otherwise we use the NNUE eval unless the
+ // PSQ advantage is decisive and several pieces remain (~3 Elo)
+ bool useClassical = !useNNUE || (pos.count<ALL_PIECES>() > 7 && abs(psq) > 1760);
if (useClassical)
v = Evaluation<NO_TRACE>(pos).value();
else