CODEWITHSUNDEEP
c#
user2948015
user2948015

Reputation: 11

C# Square root expression just won't work

I've got a very simple little program to solve quadratic equations, in the main it works but for some reason it won't calculate square roots. I just get an error saying NaN but I can't see how it's not a number?

int a = Convert.ToInt16(txta.Text);
int b = Convert.ToInt16(txtb.Text);
int c = Convert.ToInt16(txtc.Text);          

listBox1.Items.Add(Convert.ToString(Math.Sqrt(((b * b) - (4 * a * c)))));

Upvotes: 0

Views: 532

Answers (2)

Daniel Gimenez
Daniel Gimenez

Reputation: 20504

The conversions aren't the cause because if they didn't convert properly or if there was an overflow you'd get a FormatException or OverflowException respectively. None the less, since you're doing math you might want to convert to double types.

double a = Convert.ToDouble(txta.Text);
double b = Convert.ToDouble(txtb.Text);
double c = Convert.ToDouble(txtc.Text);

I believe your expression: (b * b) - (4 * a * c) is the problem. If it evaluates to a negative number, that will result in a NaN result.

See Math.Sqrt Method on MSDN for more information.

Upvotes: 3

Recursor
Recursor

Reputation: 542

It's likely getting a negative number. It might help to convert it to a double instead of an Int16, because Int16 will round every time.

Upvotes: 0

Related Questions