利用qwt进行曲线绘制的例子，能够方便进行2D曲线绘制。,Curve drawn for the use of qwt example, to facilitate drawing 2D curves.

Qwt plot example for plotting graph using time and date as a reference

关于qwt组件的小例子，测试ok,初学者注意安装的时候，QtCreator的编译版本问题-Small examples qwt components, test ok, beginner attention when installed, the compiled version of the problem QtCreator