Tweak stat bonus formula

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 507339504600cb2e49bc1cbe5c6558e59784fd86..cd435c672f877a64082689d91eb852f5fbe3eb07 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -723,10 +723,10 @@ namespace {
     else
     {
         int p = (ss-1)->statScore;
-        int malus = p > 0 ? (p + 5000) / 1024 :
-                    p < 0 ? (p - 5000) / 1024 : 0;
+        int bonus = p > 0 ? (-p - 2500) / 512 :
+                    p < 0 ? (-p + 2500) / 512 : 0;
 
-        ss->staticEval = eval = (ss-1)->currentMove != MOVE_NULL ? (pureStaticEval = evaluate(pos)) - malus
+        ss->staticEval = eval = (ss-1)->currentMove != MOVE_NULL ? (pureStaticEval = evaluate(pos)) + bonus
                                                                  : (pureStaticEval = -(ss-1)->staticEval + 2 * Eval::Tempo);
 
         tte->save(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, pureStaticEval);