[PATCH] Reduce the maximum precision for exp and log

[Joseph S. Myers]

On Thu, 28 Feb 2013, Siddhesh Poyarekar wrote:

> Hi,
> 
> The worst case precision required for exp() and log() are known[1] to
> be 158 bits and 118 bits respectively.  This patch uses this knowledge
> to limit the mp computations of both these functions to minimum
> precision larger than these values.  No regressions were seen in the
> testsuite due to this.  I could not find a slow path-invoking input
> for log, so I don't have measurements for it.  For exp however, I have
> stats on x86_64:

Please give details of your error analysis for the maximum inaccuracy in 
these implementations in glibc that shows that, together with the above 
worst-case figures, the error in the glibc implementation cannot exceed 
the distance from a half-way value.

-- 
Joseph S. Myers
joseph@codesourcery.com