On 5 janv. 2013, at 03:38, Rick Mann <rm...@latencyzero.com> wrote:

> So, we've run into an issue in our physics simulation where the floating 
> point results from cos() (and probably other intrinsics) are different 
> between Apple ARM 5 and Apple ARM 6 processors. 

This is not much of a surprise. Afaik, only 6 includes a IEEE double precision 
FPU. I suppose you do all your computations using doubles?

Depending on your requirements, you can use a simple table approach and 
interpolate between points, which is fast and somewhat inaccurate, or refine 
the result further using three or four steps of an iterative algorithm (using 
trigonometric identities, you can bring back your angle to, say, [0, pi/4] and 
perform a Taylor series approximation or something equivalent to get the final 
result).

Vincent


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