<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Apr 24, 2013, at 12:36 AM, Stephen Lin <<a href="mailto:swlin@post.harvard.edu">swlin@post.harvard.edu</a>> wrote:</div><br><blockquote type="cite">By the way, I definitely believe you that this isn't a 100% safe<br>optimization, but I'm curious, is this really guaranteed here that c<br>will not be a non-zero finite value? I was under the impression that<br>FPU state could lead to slightly different results in these kinds of<br>cases, so one should almost never rely on the result of a computation<br>being exactly zero (outside of some simple primitive cases).<br></blockquote></div><br><div>That's a common misconception. Floating point computations are deterministic and a function only of their inputs (and a couple of modal switches like rounding mode).<i> </i></div><div><br></div><div>--Owen</div></body></html>