用java实现矩阵条件数：给定矩阵A。求A的条件数，范数采用无穷范数。 输入格式： 第一行一个整数n，矩阵的行数(n<20) 接着n行，每行是矩阵的一行数据，按行顺序。每行n个实数。 输出格式： 一个实数，矩阵A的条件数，精确到小数点后4位。

以下是Java代码实现：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        double[][] matrix = new double[n][n];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                matrix[i][j] = scanner.nextDouble();
            }
        }
        double norm = 0;
        for (int j = 0; j < n; j++) {
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += Math.abs(matrix[i][j]);
            }
            if (sum > norm) {
                norm = sum;
            }
        }
        double inverseNorm = 0;
        double[][] inverseMatrix = new double[n][n];
        for (int i = 0; i < n; i++) {
            inverseMatrix[i][i] = 1;
        }
        for (int j = 0; j < n; j++) {
            for (int i = j + 1; i < n; i++) {
                double factor = -matrix[i][j] / matrix[j][j];
                for (int k = 0; k < n; k++) {
                    matrix[i][k] += factor * matrix[j][k];
                    inverseMatrix[i][k] += factor * inverseMatrix[j][k];
                }
            }
        }
        for (int j = n - 1; j >= 0; j--) {
            for (int i = j - 1; i >= 0; i--) {
                double factor = -matrix[i][j] / matrix[j][j];
                for (int k = 0; k < n; k++) {
                    matrix[i][k] += factor * matrix[j][k];
                    inverseMatrix[i][k] += factor * inverseMatrix[j][k];
                }
            }
        }
        for (int i = 0; i < n; i++) {
            double sum = 0;
            for (int j = 0; j < n; j++) {
                sum += Math.abs(inverseMatrix[i][j]);
            }
            if (sum > inverseNorm) {
                inverseNorm = sum;
            }
        }
        System.out.printf("%.4f", norm * inverseNorm);
    }
}

首先读入矩阵的行数n和矩阵本身，然后计算矩阵的无穷