This class represents a nonlinear inequality constraint, \(f(x) \leq 0\) where \(f\) is twice-differentiable.
NonlinearConstraint(f, vars_, id = NA_integer_)fA nonlinear function.
vars_A list of variables involved in the function.
.x_dim(Internal) The dimensions of a column vector with number of elements equal to the total elements in all the variables.