/usr/include/ignition/math2/ is in libignition-math2-dev 2.2.3+dfsg1-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ignition/math2/ignition/
/usr/include/ignition/math2/ignition/math/
/usr/include/ignition/math2/ignition/math.hh
/usr/include/ignition/math2/ignition/math/AffineException.hh
/usr/include/ignition/math2/ignition/math/Angle.hh
/usr/include/ignition/math2/ignition/math/Box.hh
/usr/include/ignition/math2/ignition/math/Filter.hh
/usr/include/ignition/math2/ignition/math/Frustum.hh
/usr/include/ignition/math2/ignition/math/Helpers.hh
/usr/include/ignition/math2/ignition/math/IndexException.hh
/usr/include/ignition/math2/ignition/math/Kmeans.hh
/usr/include/ignition/math2/ignition/math/Line2.hh
/usr/include/ignition/math2/ignition/math/Line3.hh
/usr/include/ignition/math2/ignition/math/Matrix3.hh
/usr/include/ignition/math2/ignition/math/Matrix4.hh
/usr/include/ignition/math2/ignition/math/Plane.hh
/usr/include/ignition/math2/ignition/math/Pose3.hh
/usr/include/ignition/math2/ignition/math/Quaternion.hh
/usr/include/ignition/math2/ignition/math/Rand.hh
/usr/include/ignition/math2/ignition/math/RotationSpline.hh
/usr/include/ignition/math2/ignition/math/SignalStats.hh
/usr/include/ignition/math2/ignition/math/Spline.hh
/usr/include/ignition/math2/ignition/math/Triangle.hh
/usr/include/ignition/math2/ignition/math/Vector2.hh
/usr/include/ignition/math2/ignition/math/Vector3.hh
/usr/include/ignition/math2/ignition/math/Vector4.hh
/usr/include/ignition/math2/ignition/math/config.hh