是否有可能确定无界变量？

如何解决是否有可能确定无界变量？

尝试求解数学程序时，出现以下错误

IPOPT terminated after exceeding the maximum iteration limit.  Hint: Remember that IPOPT is an interior-point method and performs badly if any variables are unbounded.

（我使用IPOPT是因为我认为它是唯一可用的免费求解器）

有什么方法可以确定哪些变量是无界的，以帮助调试问题？

解决方法

Drake的MathematicalProgram返回bounding_box_constraints()函数中的所有边界，您可以查询每个边界框约束并获取变量的边界。这是python代码

# We will store the lower and upper bound of each variable in x_lo and x_up.
x_lo = np.full((prog.num_vars(),),-np.inf)
x_up = np.full((prog.num_vars(),np.inf)
for bb_con in prog.bounding_box_constraints():
    # loop over each bounding box constraint
    for i in range(bb_con.variables().shape[0]):
        # loop over each variable associated with the constraint. First find the index of the variable
        var_index = int(prog.decision_variable_index()[bb_con.variables()[i].get_id()])
        # Update the lower bound for the variable.
        x_lo[var_index] = np.max((x_lo[var_index],bb_con.evaluator().lower_bound()[i]))
        # Update the upper bound for the variable.
        x_up[var_index] = np.min((x_up[var_index],bb_con.evaluator().upper_bound()[i]))
# now x_lo and x_up stores the bounds for each variable
for i in range(prog.num_vars()):
    if np.isinf(x_lo[i]) and np.isinf(x_up[i]):
        # print out the variable with no lower and upper bound.
        print(prog.decision_variables()[i])