New History Bonus Formula

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 902ba0fc6915769c157ef096f6b83340049794db..e20eed9fe1f2da39cacebcc70347d520b2bc54e9 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -376,7 +376,7 @@ void Thread::search(bool isMainThread) {
   {
       // Set up the new depth for the helper threads
       if (!isMainThread)
-          rootDepth = Threads.main()->rootDepth + Depth(int(3 * log(1 + this->idx)));
+          rootDepth = Threads.main()->rootDepth + Depth(int(2.2 * log(1 + this->idx)));
 
       // Age out PV variability metric
       if (isMainThread)
@@ -539,12 +539,7 @@ void Thread::search(bool isMainThread) {
 
 namespace {
 
-  // search<>() is the main search function for both PV and non-PV nodes and for
-  // normal and SplitPoint nodes. When called just after a split point the search
-  // is simpler because we have already probed the hash table, done a null move
-  // search, and searched the first move before splitting, so we don't have to
-  // repeat all this work again. We also don't need to store anything to the hash
-  // table here: This is taken care of after we return from the split point.
+  // search<>() is the main search function for both PV and non-PV nodes
 
   template <NodeType NT>
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) {
@@ -1100,7 +1095,7 @@ moves_loop: // When in check search starts from here
              && is_ok((ss - 1)->currentMove)
              && is_ok((ss - 2)->currentMove))
     {
-        Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY));
+        Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY -1);
         Square prevPrevSq = to_sq((ss - 2)->currentMove);
         CounterMovesStats& prevCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
         prevCmh.update(pos.piece_on(prevSq), prevSq, bonus);
@@ -1376,7 +1371,7 @@ moves_loop: // When in check search starts from here
         ss->killers[0] = move;
     }
 
-    Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY));
+    Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY -1);
 
     Square prevSq = to_sq((ss-1)->currentMove);
     CounterMovesStats& cmh = CounterMovesHistory[pos.piece_on(prevSq)][prevSq];
@@ -1406,7 +1401,7 @@ moves_loop: // When in check search starts from here
     {
         Square prevPrevSq = to_sq((ss-2)->currentMove);
         CounterMovesStats& prevCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
-        prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * depth / ONE_PLY - 1);
+        prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * ((depth + 1) / ONE_PLY));
     }
   }