Tweak reduction formula.
authorStefan Geschwentner <stgeschwentner@gmail.com>
Mon, 28 Sep 2020 20:21:14 +0000 (22:21 +0200)
committerJoost VandeVondele <Joost.VandeVondele@gmail.com>
Mon, 28 Sep 2020 20:34:25 +0000 (22:34 +0200)
commit6f0aa186d8c9ead30a107634c438c6339b9cba09
treef2aee41ccf01d0039eddecc3719390b68858cbd3
parent5efbaaba77b338dae7121c41f6590f6abc96912c
Tweak reduction formula.

Replace log(i) with log(i + 0.25 * log(i)). This increases especially for low values the reductions. But for bigger values there are nearly no changes.

STC:
LLR: 2.94 (-2.94,2.94) {-0.25,1.25}
Total: 49640 W: 5505 L: 5289 D: 38846
Ptnml(0-2): 270, 4074, 15924, 4274, 278
https://tests.stockfishchess.org/tests/view/5f71f04d3b22d6afa5069478

LTC:
LLR: 2.94 (-2.94,2.94) {0.25,1.25}
Total: 43856 W: 2209 L: 2021 D: 39626
Ptnml(0-2): 32, 1776, 18128, 1956, 36
https://tests.stockfishchess.org/tests/view/5f7232ee3b22d6afa50699a2

closes https://github.com/official-stockfish/Stockfish/pull/3163

Bench: 3555769
src/search.cpp