This is used to assign values to the templates by reference instead of making a copy . see the php manual on variable referencing for an explanation 采用引用的方式赋值到模板中，而不是在模板中创建一个数值的副本。引用的概念可以查看php手册的变量引用部分。
The arguments include variable references and an asterisk to incorporate additional arguments and the name of the source file entered at the command prompt to run the batch file 这些参数包括变量引用、用于合并其他参数的星号( * )和输入到命令提示以运行批处理文件的源文件的名称。
These are very different from xpath variable references ; they are purely string substitutions to be computed before run time , and effectively allow one to rewrite the queries using the given parameters 参数引用与xpath变量引用非常不同，它们完全是运行之前计算的串置换，使用给定的参数可以方便地改写查询。
In this method , the feedback linearization method is used to convert the nonlinear system into the linearized system , for which the tracking controller is designed , by this way , the nonlinear chaotic system can be forced to track variable reference input 在该方法中，首先采用反馈线性化方法将非线性系统转化为线性系统，再针对反馈线性化后的线性系统设计轨迹跟踪控制器，实现被控对象对于连续变化给定信号的跟踪控制。
