compile fix: forgot include for boost::math::isinf

src/primitives.cc

@@ -40,6 +40,8 @@
 #include <assert.h>
 #include <boost/assign/std/vector.hpp>
 using namespace boost::assign; // bring 'operator+=()' into scope
+
+#include <boost/math/special_functions/fpclassify.hpp>
 using boost::math::isinf;
 
 #define F_MINIMUM 0.01