由不动点线性映射产生的分形2

#include "glib.h"
int N=14;     /*递归次数*/
double sx=220.0,sy=280.0;     /*开始点坐标*/
double leng0=200.0;     /*开始点与结束点的距离*/
double a,b,t=0.5;

void fractal(double x0,double y0,double x1,double y1)  /*分形图形描画函数*/
{
  double px,py;
  if ((x1-x0)*(x1-x0)+(y1-y0)*(y1-y0)>=2.0)
  {
 px=x0+(a*(x1-x0)-b*(y1-y0));
 py=y0+(b*(x1-x0)+a*(y1-y0));
 putpixel(px,-py,15);
 fractal(x0,y0,px,py);
 fractal(px,py,x1,y1);
  }
}

void main()
{
  ginit();
  set0(sx,sy);
  a=1/(1+t*t);
  b=t/(1+t*t);
  putpixel(0,0,9);         /*描画开始点*/
  putpixel(leng0,0,12);    /*描画结束点*/
  fractal(0.0,0.0,leng0,0.0);
  gend();
}