Help with Equation in C++

[kjcheste]

I'm trying to have C++ solve an equation I have set up.
The equation is:

angle = (1/16)*(pow(LS,2) + LS*sqrt(pow(LS, 2) + pow(16,2) - 1) - 1);

where LS is a number from -1 to 1 by increasing it by 0.0001

I have angle and LS defined as double, when I run this program it tells me that the angle is equal to -1, -0, or 0 no matter what LS is.

I know that the angle should have decimal places, no idea why it keeps giving a number of 1 or 0 and not a decimal (like it should be doing)

I included the cmath and cstdlib in the program. I didn't attach the whole code, because its way too long, and I think I traced the problem down to this equation.

[Banfa]

I suspect your problem is in the (1/16) (I can't see anything else obvious). These are integers and in integer arithmatic this value is 0.

In an equation like this it is worth writting all constants as double costants rather than integer constants to ensure that you get the meaning you intend without any effects from doing integer arithmatic. This isn't hard just add .0 to all the constants e.g. (1.0/16.0).

also pow(16, 2) is a constant value, 256. You equation will be more efficient if you put in the constant value rather than calling the pow function.

And finally I am not sure that pow is a particularly efficient way of squaring, that is i Think pow(LS, 2) would be better as (LS*LS).