我正在尝试制作一个用通用公式计算二次方程答案的程序，但我遇到了一些错误。 我的Windows窗体应用程序设置方式要求a，b和c，并在通用公式中替换它们。 我有3个文本框，一个用于a，b和c的每个值，还有一个用于答案，它应该使用一个名为“calculate”的按钮。 我的问题是，当我尝试一个完美的三项式广场以外的东西时，答案就像NaN一样。 以下是我的一些代码：
private void textBox1_TextChanged(object sender, EventArgs e)
{
a = Double.Parse(textBox1.Text);
}
^这就是我为变量赋值的方式
double sqrtpart = b * b - 4 * a * c;
answer = (b + Math.Sqrt(sqrtpart)) / 2 * a;
textBox4.Text = answer.ToString();
答案 0 :(得分：4)
组2a并确保值有效（b ^ 2> 4ac）
answer = (b + Math.Sqrt(sqrtpart)) / (2 * a);
答案 1 :(得分：2)
首先，确保4ac＆lt;称b²。二次公式也使用±符号，因此我们必须创建两个单独的变量来保存两个不同的答案。
double sqrtpart = (b * b) - (4 * a * c);
answer1 = ((-1)*b + Math.Sqrt(sqrtpart)) / (2 * a);
answer2 = ((-1)*b - Math.Sqrt(sqrtpart)) / (2 * a);
textBox4.Text = answer1.ToString() + " and " + answer2.ToString();
答案 2 :(得分：0)
如果您希望计算器能够计算复数，请尝试以下
string ans = "";
double root1 = 0;
double root2 = 0;
double b = 0;
double a = 0;
double c = 0;
double identifier = 0;
a =Convert.ToDouble(Console.ReadLine());
b = Convert.ToDouble(Console.ReadLine());
c = Convert.ToDouble(Console.ReadLine());
identifier = b * b - (4 * a * c);
if (identifier > 0)
{
root1 = (-b+(Math.Sqrt(identifier)/(2*a)));
root2 = (-b - (Math.Sqrt(identifier) / (2 * a)));
string r1 = Convert.ToString(root1);
string r2 = Convert.ToString(root2);
ans = "Root1 =" + r1 + "Root2 = " + r2;
Console.WriteLine(ans);
}
if (identifier < 0)
{
double Real = (-b / (2 * a));
double Complex = ((Math.Sqrt((identifier*(-1.00))) / (2 * a)));
string SReal = Convert.ToString(Real);
string SComplex = Convert.ToString(Complex);
ans = "Roots = " + SReal + "+/-" + SComplex + "i";
Console.WriteLine(ans);
}
if (identifier == 0)
{
root1 = (-b / (2 * a));
string Root = Convert.ToString(root1);
ans = "Repeated roots : " + Root;
}
答案 3 :(得分：0)
使用以下代码：
using System;
using System.Collections.Generic;
using System.Text;
namespace SoftwareAndFinance
{
class Math
{
// quadratic equation is a second order of polynomial equation in a single variable
// x = [ -b +/- sqrt(b^2 - 4ac) ] / 2a
public static void SolveQuadratic(double a, double b, double c)
{
double sqrtpart = b * b - 4 * a * c;
double x, x1, x2, img;
if (sqrtpart > 0)
{
x1 = (-b + System.Math.Sqrt(sqrtpart)) / (2 * a);
x2 = (-b - System.Math.Sqrt(sqrtpart)) / (2 * a);
Console.WriteLine("Two Real Solutions: {0,8:f4} or {1,8:f4}", x1, x2);
}
else if (sqrtpart < 0)
{
sqrtpart = -sqrtpart;
x = -b / (2 * a);
img = System.Math.Sqrt(sqrtpart) / (2 * a);
Console.WriteLine("Two Imaginary Solutions: {0,8:f4} + {1,8:f4} i or {2,8:f4} + {3,8:f4} i", x, img, x, img);
}
else
{
x = (-b + System.Math.Sqrt(sqrtpart)) / (2 * a);
Console.WriteLine("One Real Solution: {0,8:f4}", x);
}
}
static void Main(string[] args)
{
// 6x^2 + 11x - 35 = 0
SolveQuadratic(6, 11, -35);
// 5x^2 + 6x + 1 = 0
SolveQuadratic(5, 6, 1);
// 2x^2 + 4x + 2 = 0
SolveQuadratic(2, 4, 2);
// 5x^2 + 2x + 1 = 0
SolveQuadratic(5, 2, 1);
}
}
}
这是原始source。
答案 4 :(得分：0)
有点晚了，但这是我的解决方法：
using System;
using System.Collections.Generic;
namespace MyFunctions
{
class Program
{
static void Main(string[] args)
{
printABCSolution(1, -3, 4);
printABCSolution(1, -4, 4);
printABCSolution(1, -5, 4);
printABCSolution(9, 30, 25);
printABCSolution(9, -15, 25);
Console.ReadKey();
}
private static void printABCSolution(double a, double b, double c)
{
Console.WriteLine($"Solution a={a} b={b} c={c}");
var solution = ABCMath.ABCFormula(a, b, c);
Console.WriteLine($"# Solutions found: {solution.Count}");
solution.ForEach(x => Console.WriteLine($"x={x}"));
}
}
public static class ABCMath
{
public static List<double> ABCFormula(double a, double b, double c)
{
// Local formula
double formula(int plusOrMinus, double d) => (-b + (plusOrMinus * Math.Sqrt(d))) / (2 * a);
double discriminant = b * b - 4 * a * c;
List<double> result = new List<double>();
if (discriminant >= 0)
{
result.Add(formula(1, discriminant));
if (discriminant > 0)
result.Add(formula(-1, discriminant));
}
return result;
}
}
}
输出：
Solution a=1 b=-3 c=4
# Solutions found: 0
Solution a=1 b=-4 c=4
# Solutions found: 1
x=2
Solution a=1 b=-5 c=4
# Solutions found: 2
x=4
x=1
Solution a=9 b=30 c=25
# Solutions found: 1
x=-1,66666666666667
Solution a=9 b=-15 c=25
# Solutions found: 0
答案 5 :(得分：0)
这是代码：
using System;
namespace RoomPaintCost
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("This program applies quadratic formula to Ax^2+Bx+C=0 problems");
double[] ABC= getABC();
double[] answerArray=QuadFormula(ABC);
Console.WriteLine("Positive answer: {0:0.000} \n Negative answer: {1:0.000}", answerArray[0], answerArray[1]);
}
//Form of Ax^2 + Bx + C
//Takes array of double containing A,B,C
//Returns array of positive and negative result
public static double[] QuadFormula(double[] abc)
{
NotFiniteNumberException e = new NotFiniteNumberException();
try
{
double a = abc[0];
double b = abc[1];
double c = abc[2];
double discriminant = ((b * b) - (4 * a * c));
if (discriminant < 0.00)
{
throw e;
}
discriminant = (Math.Sqrt(discriminant));
Console.WriteLine("discriminant: {0}",discriminant);
double posAnswer = ((-b + discriminant) / (2 * a));
double negAnswer = ((-b - discriminant) / (2 * a));
double[] xArray= { posAnswer,negAnswer};
return xArray;
}
catch (NotFiniteNumberException)
{
Console.WriteLine("Both answers will be imaginary numbers");
double[] xArray = { Math.Sqrt(-1), Math.Sqrt(-1) };
return xArray;
}
}
public static double[] getABC()
{
Console.Write("A=");
string sA = Console.ReadLine();
Console.Write("B=");
string sB = Console.ReadLine();
Console.Write("C=");
string sC = Console.ReadLine();
int intA = Int32.Parse(sA);
int intB = Int32.Parse(sB);
int intC = Int32.Parse(sC);
double[] ABC = { intA, intB, intC };
return ABC;
}
}
}