Re: using linux instead of osf

Michal Jaegermann (michal@ellpspace.math.ualberta.ca)
Thu, 28 Nov 1996 09:45:16 -0700 (MST)

>
> On Wed, 27 Nov 1996, Michal Jaegermann wrote:
> > >
> > > Don't quote me on the "Taylor" part.

No, it was not "Michal Jaegermann" who wrote this. Folks, can you be
a bit more careful with accreditations?

> Well, it's "taylor" to first order anyway;

That's right. Nobody was contesting that.

> > One cannot be sure without running tests with an actual code in a
> > "real life" situations, but I strongly suspect that a rational
> > approximation of a degree 3 could fare better.
>
> Digital doesn't seem to think so; there are no divisions in an objdump of
> trigonometric portions of DPML

They may be right. Like I wrote, without careful analysis of a concrete
chip and testing results, both for speed and correctnes, one cannot
tell. On the other hand it doesn't seem likely that a Taylor expansion
around zero gives a good and fast approximation on the whole interval
in question. But maybe it is competitive? I do not know at this
moment but I would be somewhat surprised.

> There's also Numerical Recipes, which is now online.
> The relevant section (in Fortran; sorry)
> http://cfatab.harvard.edu/nr/bookf.html
> section 5.11 onwards

Be careful with Numerical Recipes. This book is not famous for an
always optimal choice of algorithms and detailed numerical analysis.
I even heard some knowledgable people claiming that Numerical Recipes
influence is outright harmful (I would not go to such extremes :-).

I am afraid that we are going somewhat tangentially on Alpha, although
the issue of math libraries is really important.

Michal

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