MatrixGUI.java

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

class Matrix {
    public static double[][] inverse(double[][] ix) {
        double[][] ma = new double[ix.length][ix.length];
        for (int i = 0; i < ma.length; i++) {
            for (int j = 0; j < ma[0].length; j++) {
                ma[i][j] = ix[i][j];
            }
        }
        double[][] re = new double[ma.length][ma.length];
        int n = ma.length;
        for (int i = 0; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                ma[j][i] /= ma[i][i];
                for (int k = i + 1; k < n; k++) {
                    ma[j][k] -= ma[i][k] * ma[j][i];
                }
            }
        }
        for (int k = 0; k < n; k++) {
            for (int i = 0; i < n; i++) {
                if (i == k) {
                    re[i][k] = 1;
                } else {
                    re[i][k] = 0;
                }
            }
            for (int i = 0; i < n; i++) {
                for (int j = i + 1; j < n; j++) {
                    re[j][k] -= re[i][k] * ma[j][i];
                }
            }
            for (int i = n - 1; i >= 0; i--) {
                for (int j = i + 1; j < n; j++) {
                    re[i][k] -= ma[i][j] * re[j][k];
                }
                re[i][k] /= ma[i][i];
                if (Double.isNaN(re[i][k])) {
                    ;
                }
            }
        }
        return re;
    }
}

class MatrixPanel extends JPanel {
    private static final long serialVersionUID = 1L;
    private int n;
    private JTextField text[][];

    public MatrixPanel(int n, String tittle) {
        this.n = n;
        text = new JTextField[n][n];
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(n, n));
        setLayout(new BorderLayout());
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                text[i][j] = new JTextField(5);
                text[i][j].setText(Double.toString(0));
                panel.add(text[i][j]);
            }
        }
        add(new JLabel(tittle), BorderLayout.NORTH);
        add(panel, BorderLayout.CENTER);
    }

    public void getMatrix(double[][] a) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                a[i][j] = Double.parseDouble(text[i][j].getText());
            }
        }
    }

    public void setMatrix(double[][] a) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                text[i][j].setText(Double.toString(a[i][j]));
            }
        }
    }
}

public class MatrixGUI {
    private JButton bt1, bt2;
    private JPanel com;
    private JFrame f;
    private MatrixPanel mpB, mpA;
    private final int n = 5;
    private double[][] inv = new double[n][n];
    private double[][] mat = new double[n][n];
    private final double[][] zero = new double[n][n];

    public MatrixGUI() {
        f = new JFrame("行列計算");
        f.setSize(600, 400);
        Container c = f.getContentPane();
        mpA = new MatrixPanel(n, "行列A");
        mpB = new MatrixPanel(n, "行列B");
        c.add(mpA, BorderLayout.WEST);
        c.add(mpB, BorderLayout.EAST);
        c.add(new JLabel("=>"));
        com = new JPanel();
        bt1 = new JButton("逆行列");
        bt1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                mpA.getMatrix(mat);
                inv = Matrix.inverse(mat);
                mpB.setMatrix(inv);
            }
        });
        bt2 = new JButton("リセット");
        bt2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                mpA.setMatrix(zero);
                mpB.setMatrix(zero);
            }
        });
        com.add(bt1);
        com.add(bt2);
        c.add(com, BorderLayout.SOUTH);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);
    }

    public static void main(String args[]) {
        new MatrixGUI();
    }
}