Simplify separate malus formulas

xu-shawn · vondele · commit e2fdf6f005bd · 2025-08-24T19:55:35.000+02:00
Passed Non-regression STC: LLR: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 16352 W: 4336 L: 4090 D: 7926 Ptnml(0-2): 54, 1832, 4157, 2080, 53 https://tests.stockfishchess.org/tests/view/68a808f0b6fb3300203bca08 Passed Non-regression LTC: LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 94014 W: 24129 L: 23986 D: 45899 Ptnml(0-2): 47, 9917, 26934, 10064, 45 https://tests.stockfishchess.org/tests/view/68a8f45cb6fb3300203bcb5e closes official-stockfish#6256 Bench: 2483704
diff --git a/src/search.cpp b/src/search.cpp
@@ -1813,17 +1813,16 @@ void update_all_stats(const Position& pos,
     Piece                  movedPiece     = pos.moved_piece(bestMove);
     PieceType              capturedPiece;
 
-    int bonus        = std::min(151 * depth - 91, 1730) + 302 * (bestMove == ttMove);
-    int quietMalus   = std::min(798 * depth - 175, 2268) - 33 * quietsSearched.size();
-    int captureMalus = std::min(757 * depth - 134, 2129) - 28 * capturesSearched.size();
+    int bonus = std::min(151 * depth - 91, 1730) + 302 * (bestMove == ttMove);
+    int malus = std::min(951 * depth - 156, 2468) - 30 * quietsSearched.size();
 
     if (!pos.capture_stage(bestMove))
     {
         update_quiet_histories(pos, ss, workerThread, bestMove, bonus * 957 / 1024);
 
         // Decrease stats for all non-best quiet moves
         for (Move move : quietsSearched)
-            update_quiet_histories(pos, ss, workerThread, move, -quietMalus * 1208 / 1024);
+            update_quiet_histories(pos, ss, workerThread, move, -malus);
     }
     else
     {
@@ -1835,15 +1834,14 @@ void update_all_stats(const Position& pos,
     // Extra penalty for a quiet early move that was not a TT move in
     // previous ply when it gets refuted.
     if (prevSq != SQ_NONE && ((ss - 1)->moveCount == 1 + (ss - 1)->ttHit) && !pos.captured_piece())
-        update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,
-                                      -captureMalus * 594 / 1024);
+        update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq, -malus * 503 / 1024);
 
     // Decrease stats for all non-best capture moves
     for (Move move : capturesSearched)
     {
         movedPiece    = pos.moved_piece(move);
         capturedPiece = type_of(pos.piece_on(move.to_sq()));
-        captureHistory[movedPiece][move.to_sq()][capturedPiece] << -captureMalus * 1366 / 1024;
+        captureHistory[movedPiece][move.to_sq()][capturedPiece] << -malus * 1157 / 1024;
     }
 }
 

Original file line number	Diff line number	Diff line change
`@@ -1813,17 +1813,16 @@ void update_all_stats(const Position& pos,`
`1813`	`1813`	`Piece movedPiece = pos.moved_piece(bestMove);`
`1814`	`1814`	`PieceType capturedPiece;`
`1815`	`1815`
`1816`		`- int bonus = std::min(151 * depth - 91, 1730) + 302 * (bestMove == ttMove);`
`1817`		`- int quietMalus = std::min(798 * depth - 175, 2268) - 33 * quietsSearched.size();`
`1818`		`- int captureMalus = std::min(757 * depth - 134, 2129) - 28 * capturesSearched.size();`
	`1816`	`+ int bonus = std::min(151 * depth - 91, 1730) + 302 * (bestMove == ttMove);`
	`1817`	`+ int malus = std::min(951 * depth - 156, 2468) - 30 * quietsSearched.size();`
`1819`	`1818`
`1820`	`1819`	`if (!pos.capture_stage(bestMove))`
`1821`	`1820`	`{`
`1822`	`1821`	`update_quiet_histories(pos, ss, workerThread, bestMove, bonus * 957 / 1024);`
`1823`	`1822`
`1824`	`1823`	`// Decrease stats for all non-best quiet moves`
`1825`	`1824`	`for (Move move : quietsSearched)`
`1826`		`- update_quiet_histories(pos, ss, workerThread, move, -quietMalus * 1208 / 1024);`
	`1825`	`+ update_quiet_histories(pos, ss, workerThread, move, -malus);`
`1827`	`1826`	`}`
`1828`	`1827`	`else`
`1829`	`1828`	`{`
`@@ -1835,15 +1834,14 @@ void update_all_stats(const Position& pos,`
`1835`	`1834`	`// Extra penalty for a quiet early move that was not a TT move in`
`1836`	`1835`	`// previous ply when it gets refuted.`
`1837`	`1836`	`if (prevSq != SQ_NONE && ((ss - 1)->moveCount == 1 + (ss - 1)->ttHit) && !pos.captured_piece())`
`1838`		`- update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,`
`1839`		`- -captureMalus * 594 / 1024);`
	`1837`	`+ update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq, -malus * 503 / 1024);`
`1840`	`1838`
`1841`	`1839`	`// Decrease stats for all non-best capture moves`
`1842`	`1840`	`for (Move move : capturesSearched)`
`1843`	`1841`	`{`
`1844`	`1842`	`movedPiece = pos.moved_piece(move);`
`1845`	`1843`	`capturedPiece = type_of(pos.piece_on(move.to_sq()));`
`1846`		`- captureHistory[movedPiece][move.to_sq()][capturedPiece] << -captureMalus * 1366 / 1024;`
	`1844`	`+ captureHistory[movedPiece][move.to_sq()][capturedPiece] << -malus * 1157 / 1024;`
`1847`	`1845`	`}`
`1848`	`1846`	`}`
`1849`	`1847`