From 5f65292d114ce02fca6233420b4c3b347559c3c0 Mon Sep 17 00:00:00 2001
From: Craig Watson <craig@watsons.ch>
Date: Sat, 16 Sep 2017 19:01:00 -0400
Subject: [PATCH] Fix for qAcos occasionally returning nan for values of (not
 quite) -1 or +1

---
 src/frameworks/UBGeometryUtils.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/frameworks/UBGeometryUtils.cpp b/src/frameworks/UBGeometryUtils.cpp
index 7a9a4cbc..01c1fe1a 100644
--- a/src/frameworks/UBGeometryUtils.cpp
+++ b/src/frameworks/UBGeometryUtils.cpp
@@ -443,7 +443,8 @@ qreal UBGeometryUtils::angle(const QPointF& p1, const QPointF& p2, const QPointF
     if (a == 0 || c == 0)
         beta = 3.14159;
     else
-        beta = qAcos((a*a - b*b + c*c)/(2*a*c));
+        beta = qAcos(std::max(-1.0, std::min(1.0, (a*a - b*b + c*c)/(2*a*c))));
+
 
     return 180.* beta/3.14159;
 }