ordinarydifferentialequationtest.java

数值分析算法源码(java) 这个学期一边学习java一边学习数值分析,因此用java写了一个数值分析算法的软件包numericalAnalysis. [说明] 适合使用者:会java的

package numericalAnalysis.ode;

import java.util.Scanner;
import numericalAnalysis.function.Function;

public class OrdinaryDifferentialEquationTest {// -------------注意!!!!!!y'=f(x,y)的f(x,y)在Function接口写入-----------------------------------------
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		OrdinaryDifferentialEquation ode;
		MyFunction function;//被积函数
		String anotherChoice;// 新的方法
		String another;// 新建一个常微分方程初值问题的判断

		System.out.println("\n----------------------------本程序求解常微分方程初值问题.注意!是求其数值解"
				+ "----------------------------\n\n");
		
		do{
			//确认y'=f(x,y)的f(x,y)已经写入Function接口
			System.out.println("你要的y'=f(x,y)的f(x,y)若未在源码中写好则请先写好,若写好了请按c:\n");
			another=input.next();
			//输入初值
			System.out.println("请输入初始条件y(x0)=y0的x0:\n");
			double x0 = input.nextDouble();
			System.out.println("请输入初始条件y(x0)=y0的y0:\n");
			double y0 = input.nextDouble();
			function=new MyFunction();
			ode=new OrdinaryDifferentialEquation(function,x0,y0);//新建这个初值问题
			
			do {
				int choice = 0;
				boolean retry = true;
				while (retry) {
					retry = false;
					System.out.println();
					System.out.println("1---四阶古典龙格库塔法");
					System.out.println("2---显式四阶阿当姆斯公式");
					System.out.println("3---四阶阿当姆斯预测校正法(即隐式四阶阿当姆斯公式)");
					System.out.println("4---欧拉公式");
					System.out.println("请选择:");
					try {
						choice = Integer.parseInt(input.next());
					} catch (NumberFormatException e) {
						System.out.println("请别胡乱输入!\n");
						retry = true;
					}
				}

				switch (choice) {
				case 1:
					System.out.println("求数值解,现在构造节点!");
					System.out.println("请输入节点xi的步长:");
					double h = input.nextDouble();
					System.out.println("请输入节点xi的最大值xn:");
					double xLimit = input.nextDouble();
					
					System.out.println();
					System.out.println("结果:");
					System.out.println(ode.rungeKutta(h, xLimit));
					break;
				case 2:
					System.out.println("求数值解,现在构造节点!");
					System.out.println("请输入节点xi的步长:");
					h = input.nextDouble();
					System.out.println("请输入节点xi的最大值xn:");
					xLimit = input.nextDouble();
					
					System.out.println();
					System.out.println("结果:");
					System.out.println(ode.explicitAdams(h, xLimit));
					break;
				case 3:
					System.out.println("求数值解,现在构造节点!");
					System.out.println("请输入节点xi的步长:");
					h = input.nextDouble();
					System.out.println("请输入节点xi的最大值xn:");
					xLimit = input.nextDouble();
					
					System.out.println();
					System.out.println("结果:");
					System.out.println(ode.predictorCorrectorAdams(h, xLimit));
					break;
				case 4:
					System.out.println("求数值解,现在构造节点!");
					System.out.println("请输入节点xi的步长:");
					h = input.nextDouble();
					System.out.println("请输入节点xi的最大值xn:");
					xLimit = input.nextDouble();
					
					System.out.println();
					System.out.println("结果:");
					System.out.println(ode.euler(h, xLimit));
					break;
				}

				System.out.println("    要再使用其他方法(对于刚才这个初值问题)吗?   y/n:");
				anotherChoice = input.next();

			} while (anotherChoice.equalsIgnoreCase("y"));
		
			System.out.println("\n         输入另一个常微分方程初值问题?  y/n:");
			another = input.next();
		}while(another.equalsIgnoreCase("y"));
	}

	private static class MyFunction implements Function {
		
		public double f(double x) {
			return 0;
		}
		
		// -------------注意!!!!!!y'=f(x,y)的f(x,y)在此写入-----------------------------------------
		public double f(double x, double y) {
			return x+y;
		}
		
	}
}