example4_3.java

清华大学2002年出版的《科学与工程数值计算算法Java》配套源码

import java.applet.*;
import java.awt.*;

public class Example4_3 extends Applet
{ public static double  f(double x)
  {double y;
   y=Math.sqrt(10/(x+4));
  return y;
 }

public static double atiken(double x,double eps)
{double x0=0,x1=x,x2=0,x3=0,y=0;
 while(Math.abs(x2-x1)>eps)
 {x0=x3;x1=y;x2=f(y);
  x3=x2-(x2-x1)*(x2-x1)/(x2-2*x1+x0);
  y=f(x3);
  if(Math.abs(y)<eps)break;
  }
 return x3;
}
public void paint(Graphics g)
{double x,eps=1e-7;
 x=atiken(1.5,eps);
 g.drawString("在1.5附近的根为："+x,10,20);
}

}