why NaN number?

Question

I am trying to calculate the delta of a number using a formula of bhaskara and delta but it is giving NaN in the message box

//Variables declaration
int a = 800, b = 500, c = 350;
double delta, a1, a2;

//Formulas
delta = (b*b) - (4*a*c);
a1 = (-b + Math.Sqrt(delta)) / (2 * a);
a2 = (-b - Math.Sqrt(delta)) / (2 * a);

//Output
MessageBox.Show(a1.ToString());
MessageBox.Show(a2.ToString());

Because it can't take square root of negative number. BTW, regarding the title, NaN = "Not a Number". — Eugene Sh., Jul 02 '19 at 19:46
a negative will return NaN, from the docs https://learn.microsoft.com/en-us/dotnet/api/system.math.sqrt?view=netframework-4.8 — David Yenglin, Jul 02 '19 at 19:48

Broots Waymb · Answer 1 · 2019-07-02T19:56:13.660

2

The value of delta is -870000.
That's not a value you can take the square root of (and get a real number anyway).

From the Math.Sqrt docs:

edited Jul 02 '19 at 19:56

answered Jul 02 '19 at 19:46

Broots Waymb

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score 1 · Answer 2 · answered Jul 02 '19 at 19:53

1

As Broots said Math.sqrt of negative number will return NaN. There is a Complex struct that should do what you need:

Complex c = Complex.Sqrt(-25); // has a value of approximately 0 + 5i

answered Jul 02 '19 at 19:53

Shivam

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why NaN number?

2 Answers2