PHP has a bug...?

I was making a parabola grapher and I was testing out some values. Part of the script is to take the variable b and multiply it was negative one, then multiply by 2 times a. I entered a test value where a equals 1, b equals 0, and c equals 0. The result told me that -1 times 0 is -0. Here's the code I'm using: $x = (-1 * $b) / (2 * $a); if($x == -0) { $x = 0; } I've fixed it for now by putting the if statement, but I'm not sure why it's giving me -0. Thanks, Stephen Craton http://www.melchior.us