我不知道如何找到这两个虚数

Question

所以，我编写了一个 Java 程序来找到二次方程的解，我的问题是我似乎无法编写正确的代码来找到“虚数”，当它打印出来时，我只得到“NaN”。有什么解决办法吗？

import java.util.Scanner;
class Main {
  public static void main(String[] args) {
    
    Scanner scan = new Scanner(System.in);
    
    System.out.print("Enter the value for a: ");
    double a = scan.nextDouble();
    
    System.out.print("Enter the value for b: ");
    double b = scan.nextDouble();
    
    System.out.print("Enter the value for c: ");
    double c = scan.nextDouble();
    
    double result = b * b - 4.0 * a * c;
    
    if(result > 0.0){

      //to find two real solutions

      double x1 = (-b + Math.pow(result, 0.5)) / (2.0 * a);
      double x2 = (-b - Math.pow(result, 0.5)) / (2.0 * a);
      
      System.out.println("There are two real solutions.");
      System.out.println("x1 = " + x1);
      System.out.println("x2 = " + x2);
      
      //to find one real solution

    } else if(result == 0.0){
      double x1 = (-b / (2.0 * a));
      System.out.println("There is one real solution");
      System.out.println("x = " + x1);

      //to find the imaginary numbers

    } else if(result < 0.0){
      double x1 = (-b + Math.pow(result, 0.5)) / (2.0 * a);
      double x2 = (-b - Math.pow(result, 0.5)) / (2.0 * a);
      
      System.out.println("There are two imaginary solutions.");
      System.out.println("x1  = " + x1 + " + " + x2);
      System.out.println("x2  = " + x1 + " - " + x2);
    }
    
  }
}

Answer 1

在处理复杂的根时（当结果

1. 您正在尝试计算result 的平方根，结果为负。这将导致 NaN。正确的做法是求-result的平方根来得到你的答案。
2. 您计算根的方式不正确。两个根都有相同的实部，即-b/(2*a)，虚部的值相同，只是符号不同。

我在下面修复了您的代码以提供正确的输出。计算实部，然后计算虚部。根然后打印虚部，后缀“i”以表示虚部。

double real = -b / (2*a);
double imag = Math.pow(-result, 0.5) / (2.0 * a);

System.out.println("There are two imaginary solutions.");
System.out.println("x1  = " + real + " + " + imag + "i");
System.out.println("x2  = " + real + " - " + imag + "i");