--- a/src/types.h Sat Jun 01 22:01:27 2013 +0300 +++ b/src/types.h Sat Jun 01 22:42:52 2013 +0300 @@ -101,7 +101,7 @@ const double& z () const { return m_coords[Z]; } vertex& operator+= (const vertex& other); - vertex& operator+ (const vertex& other) const; + vertex operator+ (const vertex& other) const; vertex operator/ (const double d) const; vertex& operator/= (const double d); bool operator== (const vertex& other) const;