In mathematics, a non-autonomous system of ordinary differential equations is defined to be a dynamic equation on a smooth fiber bundle Q → → R over R . For instance, this is the case of non-relativistic non-autonomous mechanics, but not relativistic mechanics. To describe relativistic mechanics, one should consider a system of ordinary differential equations on a smooth manifold Q whose fibration over R is not fixed. Such a system admits transformations of a coordinate t on R depending on other coordinates on Q . Therefore, it is called the relativistic system. In particular, Special Relativity on the Minkowski space Q = R 4 is of this type.