java实现拉格朗日插值法

[java]代码库

import java.util.Scanner;

/*拉格朗日插值*/
public class Lagrange_interpolation {
	
	/*拉格朗日插值法*/
	private static double[] Lag_method(double X[],double Y[],double X0[]){
		int m=X.length;
		int n=X0.length;
		double Y0[]=new double[n];
		for(int i1=0;i1<n;i1++){//遍历X0
			double t=0;
			for(int i2=0;i2<m;i2++){//遍历Y
				double u=1;
				for(int i3=0;i3<m;i3++){//遍历X
					if(i2!=i3){
						u=u*(X0[i1]-X[i3])/(X[i2]-X[i3]);
					}
				}
				u=u*Y[i2];
				t=t+u;
			}
			Y0[i1]=t;
		}
		
		return Y0; 
		
	}

	public static void main(String[] args) {
		/*输入插值点横纵坐标*/
		System.out.println("Input number of interpolation point:");
		Scanner scan=new Scanner(System.in);
		int m=scan.nextInt();
		System.out.println("Input number of test point:");
		int n=scan.nextInt();
		double X[]=new double[m];
		double Y[]=new double[m];
		double X0[]=new double[n];
		System.out.println("Input the elements of X:");//已知插值点
		for(int i=0;i<m;i++){
			X[i]=scan.nextDouble();
		}
		
		System.out.println("Input the elements of Y:");//已知插值点的函数值
		for(int i=0;i<m;i++){
			Y[i]=scan.nextDouble();
		}
		
		System.out.println("Input the elements of X0:");//需要求的插值点的横坐标标值
		for(int i=0;i<n;i++){
			X0[i]=scan.nextDouble();
		}
		
		double Y0[]=Lag_method(X, Y, X0);//使用拉格朗日插值法求解得到需求插值点的纵坐标值
		System.out.println("拉格朗日插值法求解得:");
		for(int i=0;i<n;i++){
			System.out.println(Y0[i]+" ");
		}
		System.out.println();
		
		

	}

}
//源代码片段来自云代码http://yuncode.net