中文说明：在我的工作和学习中经常需要用到分段函数(piecewise function)的计算，但是很可惜的是Matlab中没有提供分段函数的直接计算函数
English Description：
In my line of work and learning often require the use of Piecewise functions (piecewise function) calculations, but it is a pity that does not provide direct calculation of Piecewise functions functions in Matlab