数据结构和算法

算法1 --- 判断一点point（x,y)是否在椭圆内（精确算法
                        var cx = this.shape.attr("cx");
var cy = this.shape.attr("cy");
var rx = this.shape.attr("rx");
var ry = this.shape.attr("ry");
var x1,y1,x2,y2;
x1 = cx - rx;
y1 = cy - ry;
        x2 = cx + rx;
        y2 = cy + ry;
        var a = Math.pow((x1-x2)/2,2) ;
        var b = Math.pow((y1 -y2)/2,2);
        var c = (x1 + x2)/2;
        var d = (y1 +y2)/2;
      if(((Math.pow(ex-c,2))/a+(Math.pow(ey-d,2))/b) <=1)
{
return true;
}
else
{
return false;
}