画曲线图工具，对于需要写文章画图，这是一个相当不错的工具，输入坐标值，绘画出漂亮的曲线图，省却自己取点的麻烦！-Painting curve tools, need to write articles for the drawing, this is a pretty good tool, enter the coordinates, painting a beautiful curve, save themselves the trouble of check points!

Xgra for linux plat form. it plots a graph in x and y dimensions. it is widely used especially with simulator software like ns2.