说明：  鲍威尔法寻找最值，S是客观功能， x0是原始点，ip: (0):不画图(错误), (>0) 画出图ip停滞, (<0) 画出值ip
(S: objective function x0: initial point ip: (0): no plot (default), (>0) plot figure ip with pause, (<0) plot figure ip )