nb The number of bilateral constraint equations (nb ≥ 0)
nk The number of edges in a polygonal approximation to a friction cone (nk ≥ 4 for contacts between three-dimensional bodies, nk = 2 for contacts between two-dimensional bodies). Note that nk = 2nr (where nr is defined immediately below).
nr Half the number of edges in a polygonal approximation to a friction cone. (nr ≥ 2 for contacts between three-dimensional bodies, nr = 1 for contacts between two-dimensional bodies).
nc The number of contact surface constraint equations.
nck The total number of edges in the polygonal approximations to the nc friction cones corresponding to the nc point contacts. Note that nck = 2ncr (where ncr is defined immediately below).
ncr Half the total number of edges in the polygonal approximations to the nc friction cones corresponding to the nc point contacts.
nv The dimension of the system generalized velocity / force.
nq The dimension of the system generalized coordinates.
v The system's generalized velocity vector (of dimension nv), which is a linear transformation of the time derivative of the system's generalized coordinates.
q The generalized coordinate vector of the system (of dimension nq).
t The system time variable (a non-negative real number).
nu The number of "generic" (non-contact related) unilateral constraint equations.
α A non-negative, real valued scalar used to correct the time derivative of position constraint errors (i.e., "stabilize" the constraints) via an error feedback process (Baumgarte Stabilization).
β A non-negative, real valued scalar used to correct position constraint errors via the same error feedback process (Baumgarte Stabilization) that uses α.
γ Non-negative, real valued scalar used to regularize constraints.