From: Marco Costalba <mcostalba@gmail.com>
Date: Mon, 28 Apr 2014 15:15:16 +0000 (+0200)
Subject: Rearrange interpolation formula
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=db229504e2c68a92177985bfbf7a870349257301;p=fairystockfish.git

Rearrange interpolation formula

Put the division at the end to reduce
rounding errors. This alters the bench
due to different rounding errors, but
should not alter ELO in any way.

bench: 7615217
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index ccc3d91..ede94ec 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -779,9 +779,9 @@ namespace {
              sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
     }
 
-    // Interpolate between a middlegame and an endgame score, scaling by 'sf'
+    // Interpolate between a middlegame and a (scaled by 'sf') endgame score
     Value v =  mg_value(score) * int(ei.mi->game_phase())
-             + eg_value(score) * int(sf) / SCALE_FACTOR_NORMAL * int(PHASE_MIDGAME - ei.mi->game_phase());
+             + eg_value(score) * int(PHASE_MIDGAME - ei.mi->game_phase()) * sf / SCALE_FACTOR_NORMAL;
 
     v /= PHASE_MIDGAME;