yade-dev team mailing list archive

[Václav Šmilauer <eu@xxxxxxxx>]

> so, for example a function that calculates axis angle, coule do a
> check if that argument to acos is higher that 1.0. And if yes - then
> perform a normalization, to bring back down that quaternion to an
> identity quaternion. This method will prevent quaternions from growin
> bigger than indentity, but will not catch quaternions that get
> smaller than identity - and that should be prevented too somehow (but
> will not produce NaNs).

I think it should be fixed in eigen, if that is a pure numerics problem.
That's why we use libs, to not do everything ourselves.

What happens if you re-normalize all quaternions before computing the
product? (just to check; I am not suggesting to do it all the time)