The existence of a true orbit near a numerically computed approximate
orbit - shadowing - of autonomous system of ordinary differential equa
tions is investigated. A general shadowing theorem for finite time, wh
ich guarantees the existence of shadowing in ordinary differential equ
ations and provides error bounds for the distance between the true and
the approximate orbit in terms of computable quantities, is proved. T
he practical use and the effectiveness of this theorem is demonstrated
in the numerical computations of chaotic orbits of the Lorenz equatio
ns.