回答編集履歴
1
multiplyメソッドを使うコードを追加
answer
CHANGED
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@@ -69,4 +69,85 @@
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69
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c.print();
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70
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}
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}
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72
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```
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**追記**
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74
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行列の掛け算をコンストラクタで実行するのではなく、
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75
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a.multiply(b) で結果の Matrix を返してくれるようにしてみました。
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76
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```Java
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import java.io.*;
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78
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79
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public class Matrix {
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80
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private int row, col;
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81
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private double[][] matrix;
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public Matrix() {}
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85
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public Matrix(int row, int col) {
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this.row = row;
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this.col = col;
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matrix = new double[row][col];
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}
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public void read(String filename) {
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try (BufferedReader br = new BufferedReader(new FileReader(filename))){
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String[] rowcol = br.readLine().split(" ");
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row = Integer.parseInt(rowcol[0]);
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col = Integer.parseInt(rowcol[1]);
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matrix = new double[row][col];
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for (int m = 0; m < row; m++) {
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String[] record = br.readLine().split(" ");
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for (int n = 0; n < col; n++)
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matrix[m][n] = Double.parseDouble(record[n]);
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}
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}
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catch (FileNotFoundException e) {
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e.printStackTrace();
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}
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catch (IOException e) {
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e.printStackTrace();
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}
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catch (NumberFormatException e) {
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e.printStackTrace();
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}
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}
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public void print() {
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for (int i = 0; i < row; i++) {
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for (int j = 0; j < col; j++)
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System.out.print(" " + matrix[i][j]);
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System.out.println();
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}
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System.out.println();
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}
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public Matrix multiply(Matrix b) {
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if (col != b.row) return null;
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Matrix c = new Matrix(row, b.col);
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for (int i = 0; i < row; i++)
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for (int j = 0; j < col; j++) {
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c.matrix[i][j] = 0;
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for (int k = 0; k < b.row; k++)
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c.matrix[i][j] += matrix[i][k] * b.matrix[k][j];
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}
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return c;
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}
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public static void main(String[] args){
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if (args.length != 2) {
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System.out.println("need two files");
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System.exit(1);
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}
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140
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Matrix a = new Matrix();
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a.read(args[0]);
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a.print();
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Matrix b = new Matrix();
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b.read(args[1]);
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b.print();
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148
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149
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Matrix c = a.multiply(b);
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c.print();
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151
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}
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152
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}
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72
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```
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