title: When do I use fabs and when is it sufficient to use std::abs?
body: <p>I assume that <code>abs</code> and <code>fabs</code> are behaving different when using <code>math.h</code>. But when I use just <code>cmath</code> and <code>std::abs</code>, do I have to use <code>std::fabs</code> or <code>fabs</code>? Or isn't this defined?</p>