对mapinfo中选定区域用指定半径的圆填充，计算填充圆的个数，并计算填充圆的面积与区域面积之比-right MapInfo selected regional specified radius of the circle to fill the calculation filled round number, and calculate an area filled with a round of the regional area ratio

包括部分空间算法，如计算两坐标点距离、判断两坐标点是否相等、计算叉积、计算点积、判断点p是否在线段l上、计算点bp以点op为圆心逆时针旋转dAlpha(单位：弧度)后所在的坐标点位置、计算指定半径圆上指定角度的弦长、计算由起点坐标和终点坐标构成的线段在指定距离和指定方向的垂点坐标等空间算法-Including some space algorithms, such as calculating the distance between the two coordinates to determi

缓冲区计算与显示程序 在程序中交互的画出多线，根据设置的缓冲区半径，自动计算并绘制出缓冲区-Buffer calculation and display program in the program to draw multi-line interaction, according to the setting of the buffer radius, automatically calculate and draw the buffer

利用C语言计算地图投影中的曲率半径及纬线半径-C language is used to calculate the radius of curvature radius and parallel map projection