diff --git a/chesspi/chesspi_ai.cpp b/chesspi/chesspi_ai.cpp
index 2a67da046b819360ad57b739aed168d313a6aaa1..3ed630a46475aa545671095fd94247e292fc4ffa 100644
--- a/chesspi/chesspi_ai.cpp
+++ b/chesspi/chesspi_ai.cpp
@@ -173,17 +173,17 @@ size_t judge_tree(std::vector<chess_node> & tree)
 	{
 		if (tree[i].side==0)
 		{
-			float ratio = (tree[i].jump_cost[1]+1) / (tree[i].jump_cost[0]+1)/sqrt(tree[i].jump_cost[0]+1);
+			float ratio = sqrt((tree[i].jump_cost[1]+1) / (tree[i].jump_cost[0]+1)/ (tree[i].jump_cost[0]+1));
 			tree[i].weight = ratio;
 		}
 		else
 		{
-			float ratio = (tree[i].jump_cost[0]+1) / (tree[i].jump_cost[1]+1)/sqrt(tree[i].jump_cost[0]+1);
+			float ratio = sqrt((tree[i].jump_cost[0]+1) / (tree[i].jump_cost[1]+1)/ (tree[i].jump_cost[1]+1));
 			tree[i].weight = ratio;
 		}
 		size_t parent = tree[i].parent;
-		tree[parent].jump_cost[0] += tree[i].jump_cost[0] * tree[i].weight/tree[i].depth;
-		tree[parent].jump_cost[1] += tree[i].jump_cost[1] * tree[i].weight/tree[i].depth;
+		tree[parent].jump_cost[0] += tree[i].jump_cost[0] * tree[i].weight/tree[i].depth/tree[i].depth;
+		tree[parent].jump_cost[1] += tree[i].jump_cost[1] * tree[i].weight/tree[i].depth/tree[i].depth;
 		--i;
 		if (i%1000==0)
 			printf ("Sorting.%d...  \r",total_nodes - i);