From: H. Felix Wittmann <hfwittmann@gmail.com>
Date: Thu, 2 Jan 2014 12:00:48 +0000 (+0100)
Subject: Ensure move_importance() is non-zero
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=8454d871ec105749fb5e2e7e9aea9e7c25cfdf6e;hp=153309e28702d8e5f49f4772bfb61f9f9ed965fc;ds=inline

Ensure move_importance() is non-zero

In case ply is very high, function will round
to zero (although mathematically it is always
bigger than zero). On my system this happens at
movenumber 6661.

Although 6661 moves in a game is, of course,
probably impossible, for safety and to be locally
consistent makes sense to ensure returned value
is positive.

Non functional change.
---

diff --git a/src/timeman.cpp b/src/timeman.cpp
index 9accfbb3..0348b677 100644
--- a/src/timeman.cpp
+++ b/src/timeman.cpp
@@ -18,6 +18,7 @@
 */
 
 #include <algorithm>
+#include <cfloat>
 #include <cmath>
 
 #include "search.h"
@@ -44,7 +45,7 @@ namespace {
 
   double move_importance(int ply) {
 
-    return pow((1 + exp((ply - xshift) / xscale)), -skewfactor);
+    return pow((1 + exp((ply - xshift) / xscale)), -skewfactor) + DBL_MIN; // Ensure non-zero
   }