  Stochastic variational integrators for constrained, stochastic mechanical
systems are developed in this paper. The main results of the paper are twofold:
an equivalence is established between a stochastic Hamilton-Pontryagin (HP)
principle in generalized coordinates and constrained coordinates via Lagrange
multipliers, and variational partitioned Runge-Kutta (VPRK) integrators are
extended to this class of systems. Among these integrators are first and
second-order strongly convergent RATTLE-type integrators. We prove order of
accuracy of the methods provided. The paper also reviews the deterministic
treatment of VPRK integrators from the HP viewpoint.
