example6_8.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.awt.*;
import java.applet.*;
public class Example6_8 extends Applet
{
 public static double f(double x)
 {double y;
  y=Math.cos(x)+Math.pow(x,6);
  return y; }

 public static double GaussHermite(int n)
  {double s;
   double[] y=new double[5];
   double[] x=new double[5];
   int i;
   if(n==1){x[0]=0;y[0]=1.7724539;}
   else if(n==2){x[0]=-0.707107;x[1]=0.707107;y[0]=y[1]=0.8862269;}
   else if(n==3){x[0]=-1.224745;x[1]=0;x[2]=1.224745;
                 y[0]=y[2]=0.2954090;y[1]=1.1816359;}
   else if(n==4){x[0]=-1.650680;x[1]=-0.5246481;x[2]=0.524648;x[3]=1.650680;
                 y[0]=y[3]=0.0813128;y[1]=y[2]=0.8049141;}
   else if(n==5){x[0]=-2.020183;x[1]=-0.958572;x[2]=0;x[3]=0.958572;x[4]=2.020183;
                 y[0]=y[4]=0.0199532;y[1]=y[3]=0.3936193;y[2]=0.9453087;}
   s=0;
   for(i=0;i<n;i++){s+=y[i]*f(x[i]);}
   return s;

}
public void paint(Graphics g)
{double y;
 int n;
 for(n=1;n<=5;n++)
 {y=GaussHermite(n);
  g.drawString("I"+n+"="+y,10,20*n);
 }
}}