(2nd time) tweaks to erff() threshold values

[Steve Kargl]

On Sat, Aug 24, 2013 at 07:30:29PM -0700, Steve Kargl wrote:
> On Sat, Aug 24, 2013 at 01:21:02PM -0700, Steve Kargl wrote:
> > On Fri, Aug 23, 2013 at 09:57:44AM -0700, Steve Kargl wrote:
> > > On Fri, Aug 23, 2013 at 09:12:33PM +1000, Bruce Evans wrote:
> > > 
> > >> The whole erf implementation is probably not the best way for
> > >> float precision, but is good for understanding higher precisions.
> > > 
> > > I'm fairly certain that the implementation of erff() is not very
> > > efficient.  The polynomials, used in the rational approximations,
> > > are the same order as those used in the double precision approximation.
> > > I'll check the polys when update my P(x)/Q(x) remes algorithm for
> > > erfl and erfcl.
> > 
> > I seem to be right (although I haven't iterated on the P's and Q's).
> > 
> 
> Now, with pretty testing and (perhaps) better coefficients:
> 

LMAO.  I have not idea where "pretty" came from.  s/pretty/better
-- 
Steve