First off, I wasn't sure whether to put this in Math and Science or here, but I'm putting it here.

In .NET, Math.Tan returns the tangent of some number in radians. However, I need the tangent of that number in degrees. I wrote myself a little method, but for some reason, it's not producing the correct number. I take the degrees in radians, multiply them by pi, then divide by 180.

When I put in 30.0, I should get 0.577350269... (according to the calculator) but I'm getting 0.523598775... Am I doing something wrong, or is it an error by the computer?

Full method:
public double RadToDeg(double rad) {
    double deg = ((rad * Math.PI) / (double)180);
    return deg;
}

EDIT: I also tried moving around the parenthesis so it was "rad * (Math.PI / (double)180)," but there was no change.

C#

Doubles are more precise floating-point numbers (doubles = 15 sig digs, floats = 7 sig digs), so not sure if that would help.

Edit: Nope, doesn't change it.

Yeah, but when I do that I get 1718.873385...

I'm pretty sure the problem is that your conversion factor is inverted. Degrees = radians * 180 / pi.

Actually, he seems to be converting from degrees to radians (30 to π/6). I'm guessing his routine is just marked wrong.

But you're saying you want to type in 30 and get 0.577, which is degrees. You want to convert degrees to radians, then put it in Math.Tan.

Quote from: BlakPilar on October 08, 2011, 06:11:56 pm

@parser, check the category this is computer languages help.

yeah but you said that your answer on calc differed from your comp.

The calculator is probably right. He's having trouble writing a math function in C#.

Quote from: BlakPilar on October 08, 2011, 06:11:56 pm

@parser, check the category this is computer languages help.

yeah but you said that your answer on calc differed from your comp.

Like Deep said lol. I did tan(30(degree symbol)) to be sure

But I got it now.