Simplify move_importance(): take 3

[stockfish] / src / timeman.cpp

diff --git a/src/timeman.cpp b/src/timeman.cpp
index 81c2f39b77e4d40eaff30c57dadeeda6f4f2b1be..5e9304d5c15a4385752a7ec48c96ad98283e415a 100644 (file)
--- a/src/timeman.cpp
+++ b/src/timeman.cpp
@@ -34,8 +34,6 @@ namespace {
 
   const double xscale     = 9.3;
   const double xshift     = 59.8;
-  const double yscale     = 7780;
-  const double yshift     = 1e-3; // Larger than 0. Ensures a non-zero importance
   const double skewfactor = 0.172;
 
 
@@ -46,7 +44,7 @@ namespace {
 
   double move_importance(int ply) {
 
-    return yscale / pow((1 + exp((ply - xshift) / xscale)), skewfactor) + yshift;
+    return pow((1 + exp((ply - xshift) / xscale)), -skewfactor);
   }