说明：  由于BP网络的权值优化是一个无约束优化问题，而且权值要采用实数编码，所以直接利用Matlab遗传算法工具箱。以下贴出的代码是为一个19输入变量，1个输出变量情况下的非线性回归而设计的，如果要应用于其它情况，只需改动编解码函数即可。
(As a result of BP network weights optimization is a constrained optimization problems, and weights to be used real-coded, so the direct use of Matlab genetic algorithm toolbox. Posted the following code is for a 19 input variables, an output variable in case of non-linear regression designed, if applied to other situations, simply change your codec function.)