<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - dEQP-GLES3: sin, cos, tan do not have enough precision" href="https://bugs.freedesktop.org/show_bug.cgi?id=89634#c1">Comment # 1</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - dEQP-GLES3: sin, cos, tan do not have enough precision" href="https://bugs.freedesktop.org/show_bug.cgi?id=89634">bug 89634</a> from <a class="email" href="mailto:kenneth@whitecape.org" title="Kenneth Graunke <kenneth@whitecape.org>"> Kenneth Graunke</a> <pre>From the IVB PRM, Volume 4, Part 3: "Absolute error <= 0.0008 for the range of +/- 100* pi Outside of the above range the function will remain periodic, producing values between -1 and 1. However, the period of COS is determined by the internal representation of Pi, meaning that as the magnitude of input increases the absolute error will, in general, also increase." Given that sin and cos are extremely common in shaders, I'm rather loathe to emit extra shader instructions to try and make them more precise. I imagine most angles used by real programs will be between [-100pi, 100pi]. You can definitely construct cases that break (even producing surprising results like sin(x) > 1.0), but as you say, the specification specifically states that there is no precision guarantee.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>