面积法计算图像的分维，前面几行表示用一曲线扩展为曲面，请根据自己的实际情况改动-Area method to calculate the fractal dimension images, in front of a few lines with a curve that extended to surface, please according to their own changes to the actual situation

设计并测试一个名为Rectangle的矩形类，其属性为矩形的左下角与右上角两个点的坐标，能计算矩形的面积。-Design and test a Rectangle called the rectangular types, the property of the top right corner of the rectangular with two point coordinates, can calculate the area of the Rectangle