数值分析实验报告之二分法求根 java

1、数值分析实验报告 实验三 非线性方程求根一、实验目的1掌握二分法、牛顿迭代法等常用的非线性方程迭代算法；2培养编程与上机调试能力。二、实验要求1用C语言设计出二分法和牛顿法的程序，并且选择不同的初值，观察所需的迭代次数和迭代结果。三、实验原理1二分法计算f(x)=0的二分法如下： 输入求根取间a,b和误差控制量，定义函数f(x)。 如果 ，转；否则退出选用其它求根方法 当|a-b|>时，计算中点x=(a+b)/2以及f(x)的值； 分情况处理 ：停止计算，转：修正区间 ：修正区间 输出近似根四、实验内容1.用二分法求方程在区间1.0,1.5内的一个实根，要求精确到小数点后2位。五、实验结

2、果输入零点所在区间时：输入错误的区间时： 二分法程序代码：import java.awt.Container;import java.awt.Dimension;import java.awt.EventQueue;import java.awt.GridLayout;import java.awt.Toolkit;import javax.swing.JFrame;import javax.swing.JPanel;import java.awt.Color;import javax.swing.JLabel;import java.awt.Font;import javax.swing.J

3、TextField;import javax.swing.JButton;import javax.swing.SwingConstants;import java.awt.FlowLayout;import java.awt.event.ActionListener;import java.awt.event.ActionEvent;public class Erfenfaa implements ActionListenerJFrame frame;private JTextField textField1;private JTextField textField2;private JTe

4、xtField textField3;private JTextField textField4; JPanel panel_1 ,panel_2 ,panel_22,panel_3 ,panel_4 ; JLabel label1,label2,labelaa,labelbb,label_2,label_3; JButton submit,cancel;/* * Launch the application. */public static void main(String args) EventQueue.invokeLater(new Runnable() public void run

5、() try new Erfenfaa(); catch (Exception e) e.printStackTrace(););/* * Create the frame. */public Erfenfaa() frame = new JFrame("二分法解方程");frame.setSize(380,480);frame.setVisible(true);frame.setContentPane(createcontentPane();frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);centerFrame()

6、;/frame.setBounds(100, 100, 396, 300);frame.setResizable(false);public Container createcontentPane()Container contentPane=frame.getContentPane();contentPane.setLayout(new GridLayout(5,1,5,0);/由上至下 4行1列 panel_1 = new JPanel();/面板panel_1放置label1和label2 panel_1.setLayout(new FlowLayout(FlowLayout.CENTE

7、R,5,35);panel_1.setBackground(Color.WHITE);label1 = new JLabel("二分法解方程");label1.setFont(new Font("宋体", Font.BOLD, 18);panel_22= new JPanel();/面板panel_1放置label1和label2 panel_22.setLayout(new FlowLayout(FlowLayout.CENTER,5,35); panel_22.setBackground(Color.WHITE); label2 = new JLab

8、el("y=x3-x-1");label2.setBounds(180, 41, 101, 24); panel_2 = new JPanel();/面板jpanel_2放置a,b,控制误差量 panel_2.setBackground(Color.WHITE);panel_2.setLayout(null);labelaa= new JLabel("请输入区间a,b中的a:"); labelaa.setFont(new Font("宋体", Font.BOLD, 12);labelaa.setBounds(80, 10, 172,

9、15);textField1 = new JTextField(10);/textField1输入a的值 textField1.setBounds(219, 7, 42, 21);labelbb = new JLabel("请输入区间a,b中的b:");labelbb.setFont(new Font("宋体", Font.BOLD, 12);labelbb.setBounds(80, 38, 172, 15);textField2 = new JTextField(10);/textField2输入b的值 textField2.setBounds(21

10、9, 35, 42, 21);label_2 = new JLabel("请输入控制误差量:");label_2.setFont(new Font("宋体", Font.BOLD, 12);label_2.setBounds(80, 63, 117, 15);textField3 = new JTextField(10); /textField3输入控制误差量textField3.setBounds(191, 60, 66, 21); panel_3 = new JPanel();/面板panel_3放置确定和取消按钮panel_3.setBackgro

11、und(Color.WHITE);panel_3.setLayout(new FlowLayout(FlowLayout.CENTER,20,30);submit = new JButton("确定");/确定按钮submit.addActionListener(this);submit.setHorizontalAlignment(SwingConstants.CENTER);cancel = new JButton("取消");/取消按钮cancel.addActionListener(this);cancel.setHorizontalAlignm

12、ent(SwingConstants.CENTER);panel_4 = new JPanel();/面板panel_4放置“方程解”标签和输出解文本块panel_4.setBackground(Color.WHITE);panel_4.setLayout(new FlowLayout(FlowLayout.CENTER,5,30);label_3 = new JLabel("方程解为：");label_3.setFont(new Font("宋体", Font.BOLD, 12);label_3.setBounds(24, 8, 65, 15);tex

13、tField4 = new JTextField();/输出解或区间范围不对textField4.setBounds(99, 5, 97, 15);textField4.setColumns(25);panel_1.add(label1);panel_22.add(label2);panel_2.add(labelaa);panel_2.add(textField1);panel_2.add(labelbb);panel_2.add(textField2);panel_2.add(label_2);/控制误差量panel_2.add(textField3);panel_3.add(submit

14、);panel_3.add(cancel);panel_4.add(label_3);panel_4.add(textField4);contentPane.add(panel_1);contentPane.add(panel_22);contentPane.add(panel_2); contentPane.add(panel_3);contentPane.add(panel_4);return contentPane;public void centerFrame()/窗口居中 int x,y,screenWidth,screenHeight,frameWidth,frameHeight;

15、 Dimension screenSize=Toolkit.getDefaultToolkit().getScreenSize(); screenWidth=screenSize.width;/取得屏幕宽度和高度 screenHeight=screenSize.height; frameWidth=frame.getWidth(); frameHeight=frame.getHeight(); x=(screenWidth-frameWidth)/2; y=(screenHeight-frameHeight)/2; frame.setLocation(x,y);public void acti

16、onPerformed(ActionEvent e) /事件触发JButton button=(JButton)e.getSource();float a,b,p,w;if(button=submit)String o=textField1.getText();String l=textField2.getText();String m=textField3.getText(); a= Float.parseFloat(o); b= Float.parseFloat(l); p= Float.parseFloat(m); w=b-a;if(z(a,b)=true)textField4.setT

17、ext(String.valueOf(fun(w,b,a,p);/浮点型强制转换为字符型 if(z(a,b)=false)textField4.setText(String.valueOf("方程值不在所输入的区间内，请选择其他方法"); if(button=cancel)textField1.setText("");textField2.setText("");textField3.setText(""); public static boolean z(float a,float b)/判断区间是否包括零点 float a11=y(a); float a21=y(b); if(a11*a21)<0) return true; else return false; public static float y(float x)/设置y的函数，y=x3-x-1 float y;