  Until now only for specific crossovers between Poissonian statistics (P), the
statistics of a Gaussian orthogonal ensemble (GOE), or the statistics of a
Gaussian unitary ensemble (GUE) analytical formulas for the level spacing
distribution function have been derived within random matrix theory. We
investigate arbitrary crossovers in the triangle between all three statistics.
To this aim we propose an according formula for the level spacing distribution
function depending on two parameters. Comparing the behavior of our formula for
the special cases of P$\rightarrow$GUE, P$\rightarrow$GOE, and
GOE$\rightarrow$GUE with the results from random matrix theory, we prove that
these crossovers are described reasonably. Recent investigations by
F.~Schweiner~\emph{et al.} [Phys. Rev. E~\textbf{95}, 062205 (2017)] have shown
that the Hamiltonian of magnetoexcitons in cubic semiconductors can exhibit all
three statistics in dependence on the system parameters. Evaluating the
numerical results for magnetoexcitons in dependence on the excitation energy
and on a parameter connected with the cubic valence band structure and
comparing the results with the formula proposed allows us to distinguish
between regular and chaotic behavior as well as between existent or broken
antiunitary symmetries. Increasing one of the two parameters, transitions
between different crossovers, e.g., from the P$\rightarrow$GOE to the
P$\rightarrow$GUE-crossover, are observed and discussed.
