From a1b737c049bb297d5e4ec80cd5335d1382ce623a Mon Sep 17 00:00:00 2001
From: Jaron Kent-Dobias <jaron@kent-dobias.com>
Date: Sat, 14 Dec 2019 11:07:35 -0500
Subject: efficiency tuning: don't evaluate the exponential when we don't have
 to

---
 lib/wolff.hpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/wolff.hpp b/lib/wolff.hpp
index d21d788..23df10c 100644
--- a/lib/wolff.hpp
+++ b/lib/wolff.hpp
@@ -239,7 +239,11 @@ namespace wolff{
               }
 
 #ifndef WOLFF_USE_FINITE_STATES
-              p = 1.0 - exp(-dE / T);
+              if (dE < 0) {
+                p = 0;
+              } else {
+                p = 1.0 - exp(-dE / T);
+              }
 #endif
 
               if (dist(rng) < p) {
-- 
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