?? example4_2.java
字號:
import java.applet.*;
import java.awt.*;
public class Example4_2 extends Applet
{public static double f(double x)
{double y;
y=x*x*(x*x-4)+4;
//y=x*x*(x+4)-10;
return y;
}
public static double Df(double x)
{double y;
//y=(3*x+8)*x;
y=x*(4*x*x-8);
return y;
}
public static double D2f(double x)
{double y;
y=12*x*x-8;
//y=6*x+8;
return y;
}
public static double newton(double x,double eps)
{double x1=x,x2=0,d0,d1,d2;
while(Math.abs(x2-x1)>eps)
{x2=x1;d0=f(x1);d1=Df(x1);
if(Math.abs(d0)<eps)break;
if(Math.abs(d1)<eps){d2=D2f(x1);x1=x1-d0*d1/(d1*d1-d0*d2);}
else x1=x1-d0/d1;
}
return x1;
}
public void paint(Graphics g)
{double x,eps=1e-7;
x=newton(1.5,eps);
g.drawString("在1.5附近的根為:"+x,10,20);
}
}
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