数组处理代码

• 1 找数组中的最大元素

    public static double max(double[] a) {
        double max = a[0];
        for (int i = 0; i < a.length; i++) {
            if (a[i] > max) {
                max = a[i];
            }
        }
        return max;
    }

• 2 计算数组元素的平均值

    public static double average(double[] a) {
        int N = a.length;
        double sum = 0.0;
        for (int i = 0; i < N; i++) {
            sum += a[i];
        }
        return sum / N;
    }

• 3 复制数组

    public static double[] copy(double[] a) {
        int N = a.length;
        double[] b = new double[N];
        for (int i = 0; i < N; i++) {
            b[i] = a[i];
        }
        return b;
    }

• 4 颠倒数组元素的顺序

    public static void reverse(double[] a) {
        int N = a.length;
        for (int i = 0; i < N / 2; i++) {
            double temp = a[i];
            a[i] = a[N - 1 - i];
            a[N - 1 - i] = temp;
        }
    }

• 5 矩阵相乘（方阵）

    public static double[][] matrixMultiplication(double[][] a, double[][] b) {
        int N = a.length;
        double[][] c = new double[N][N];
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                for (int k = 0; k < N; k++) {
                    c[i][j] += a[i][k] * b[k][j];
                }
            }
        }
        return c;
    }