C++ Mathematical Expression Library (ExprTk)  http://www.partow.net/programming/exprtk/index.html

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index 3f7ada7..d88c773 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,9 @@
 language: cpp
 
+sudo: required
+
+dist: trusty
+
 compiler:
   - gcc