From 7bd32a51f5410cc0eab2f1ef44ceb7f650677c02 Mon Sep 17 00:00:00 2001
From: FauziAkram <fauzi.dabat@hotmail.com>
Date: Mon, 4 May 2026 08:30:28 +0200
Subject: [PATCH] Replacing the futility margin static value with a continuous
 transition

Smooth the futility margin by interpolating the multiplier based on depth, replacing the previous static value with a continuous transition between depth 1 and 10.

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 208448 W: 53891 L: 53324 D: 101233
Ptnml(0-2): 629, 24426, 53574, 24939, 656
https://tests.stockfishchess.org/tests/view/69e232206f344a19176002f3

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 208938 W: 53432 L: 52765 D: 102741
Ptnml(0-2): 105, 22531, 58550, 23158, 125
https://tests.stockfishchess.org/tests/view/69e8b5d00e9667dd5a7656c6

closes https://github.com/official-stockfish/Stockfish/pull/6780

Bench: 2661424
---
 src/search.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/search.cpp b/src/search.cpp
index 282b379b6..4716e332e 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -916,7 +916,9 @@ Value Search::Worker::search(
     if (!ss->ttPv && depth < 15 && eval >= beta && (!ttData.move || ttCapture) && !is_loss(beta)
         && !is_win(eval))
     {
-        Value futilityMult   = 76 - 21 * !ss->ttHit;
+        Value futilityMult = interpolate(std::min(int(depth), 10), 1, 10, 40, 76);
+        futilityMult -= 21 * !ss->ttHit;
+
         Value futilityMargin = futilityMult * depth
                              - (2686 * improving + 362 * opponentWorsening) * futilityMult / 1024
                              + std::abs(correctionValue) / 180600;