This simplifies a `* 99 / 1300` term into just `/ 13`.
Passed non-regression STC:
LLR: 2.92 (-2.94,2.94) <-1.75,0.25>
Total: 58816 W: 15727 L: 15540 D: 27549
Ptnml(0-2): 149, 6370, 16203, 6517, 169
https://tests.stockfishchess.org/tests/view/
647d25e4726f6b400e408165
Passed non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 154386 W: 41749 L: 41669 D: 70968
Ptnml(0-2): 94, 14992, 46956, 15042, 109
https://tests.stockfishchess.org/tests/view/
647d9b3c726f6b400e408b2a
closes https://github.com/official-stockfish/Stockfish/pull/4608
Bench:
2511327
&& (ss-1)->statScore < 17329
&& eval >= beta
&& eval >= ss->staticEval
- && ss->staticEval >= beta - 21 * depth - improvement * 99 / 1300 + 258
+ && ss->staticEval >= beta - 21 * depth - improvement / 13 + 258
&& !excludedMove
&& pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly))