Summary: "In this paper the method of design of kinematical and dynamical equations of mechanical systems, applied to numerical realization, is proposed. The corresponding difference equations which are obtained give a guarantee of computations with a given precision. The equations of programmed constraints and those of constraint perturbations are found. The stability of the programmed manifold for numerical solutions of the kinematical and dynamical equations is obtained by the corresponding construction of the constraint perturbation equations. The dynamical equations of a system with programmed constraints are set up in the form of Lagrange's equations in generalized coordinates. Certain inverse problems of rigid body dynamics are examined."