  In this work is discussed possibility and actuality of Lagrangian approach to
quantum computations. Finite-dimensional Hilbert spaces used in this area
provide some challenge for such consideration. The model discussed here can be
considered as an analogue of Weyl quantization of field theory via path
integral in L. D. Faddeev's approach. Weyl quantization is possible to use also
in finite-dimensional case, and some formulas may be simply rewritten with
change of integrals to finite sums. On the other hand, there are specific
difficulties relevant to finite case.
