java数学函数f(x)

Question

我正在尝试创建一个数学函数:f(x)= x - 3 /(x*x) - 4.它有用户输入x的值(x是"a"),但我不知道如何让它在函数中使用x.

public static void main(String[] args) {
    double z = f(1);
    System.out.println("Answer: " + z);
}

public static double f(double x) {
    double y = 0;
    String a = "";
    Scanner reader = new Scanner(System.in);
    System.out.println("Enter value for 'x': ");
    a = reader.nextLine();
    y = a - 3 / (a * a) - 4);
    return y;
}

Answer 1

您正在寻找的用户输入的是nextDouble(),而不是nextLine返回a String而不是a double.此外,处理用户在外部的输入更有意义function,并将输入作为参数传递.所以它看起来像这样:

public static void main(String[] args) {
    double a;
    Scanner reader = new Scanner(System.in);
    System.out.println("Enter value for 'x': ");
    a = reader.nextDouble();
    double z = f(a);
    System.out.println("Answer: " + z);
}

public static double f(double x) {
    return x - 3 / (x * x) - 4;
}