BtoVVana: the package for analysis of B_s⁰to J/psiφ and B_d⁰to J/psi K^* decays

C++ package {\tt BtoVVana} is aimed to extract physics parameters in decays of the scalar neutral B-meson to two vector particles in the intermediate state, and two leptons and two pseudoscalar mesons in the final state. Improved angular moments method is implemented in the package {\tt BtoVVana}: the method uses the time dependent weighting functions and time-integrated observables with variable upper time limit. These observables allow to keep full time informative contents of the decay. By using the package {\tt BtoVVana} it was shown that the statistical errors of extraction of the observables strongly depends on the choice of the angular weighting functions. The best angular weighting functions, which are the linear combinations of the amplitude angular functions, are implemented in the package {\tt BtoVVana}. The first version of the program contains algorithms to extract physics parameters in the case of untagged decays. The package {\tt BtoVVana} and program codes for the channels $B_s^0\to J/\psi\phi$ and $B_d^0\to J/\psi K^*$ in the Monte Carlo generator {\tt SIMUB} were written in parallel and mutually tested with high precision.