四叶草

在图形输出窗口中动态绘制四叶草。
 1 #include <graphics.h>
 2 #include <math.h>
 3 #include <conio.h>
 4 #define PI 3.1415926535
 5 void main(void)
 6 {
 7     initgraph(640,480);
 8     setcolor(GREEN);
 9     setorigin(320,240);
10     double e;
11     int x1,y1,x2,y2;
12     for(double a=0;a<2*PI;a+=2*PI/720)
13     {
14         e=100*(1+sin(4*a));
15         x1=(int)(e*cos(a));
16         y1=(int)(e*sin(a));
17         x2=(int)(e*cos(a+PI/5));
18         y2=(int)(e*sin(a+PI/5));
19         line(x1,y1,x2,y2);
20         Sleep(20);
21     }
22     getch();
23     closegraph();
24 }