integration.java

来自「数值计算（科学计算）实验代码高斯消元楚列斯基分解」· Java 代码 · 共 51 行

import java.math.*;
public class Integration {
	public double midpoint(double a,double b)
	{
		double mf=(b-a)*this.fx((a+b)/2);
		return mf;
	}
	public double trapezoid(double a,double b)
	{
		
		double tf=(b-a)/2*(this.fx(a)+this.fx(b));
		return tf;
		
	}
	public double simpson(double a,double b)
	{
		
		double sf=(b-a)/6*(this.fx(a)+this.fx(b)+4*fx((a+b)/2));
		return sf;
		
	}
	public double fx(double x)
	{
		x=4/(1+Math.pow(x, 2));
		return x;
	}
	public static void main(String[] args)
	{
		Integration  aaa=new Integration();
		//double m=aaa.midpoint(0, 1);
		double a=0;
		double m=0;
		double t=0;
		double s=0;
		for(int i=0;i<10;i++)
		{  
			double buchang=(double)(1-0)/10;
			
			m=m+aaa.midpoint(a,a+buchang);
			t=t+aaa.trapezoid(a,a+buchang);
			s=s+aaa.simpson(a,a+buchang);
			a=a+buchang;
	
		}
		System.out.println(m);
		System.out.println(t);
		System.out.println(s);
	}

}