Message-ID: <36503E66.BE49C47B@cyberoptics.com>
From: Eric Rudd <rudd AT cyberoptics DOT com>
Organization: CyberOptics
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Subject: Re: high precision nonlinear math functions ?
References: <Pine DOT SUN DOT 3 DOT 91 DOT 981115130608 DOT 1381G-100000 AT is> <4 DOT 1 DOT 19981116091759 DOT 00abe6f0 AT hal DOT nt DOT tuwien DOT ac DOT at>
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Date: Mon, 16 Nov 1998 09:01:59 -0600
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To: djgpp AT delorie DOT com
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Anton Helm wrote:

> After receiving several messages about my "stupid coding"
> (yes someone actually used this wording...)

I don't know what it is about E-mail that provokes people to intemperance...

> I testify here and now that I did _NOT_ implement the examples given
> directly. The code is heavily rearranged to take care of numerical
> effects. I just didn't want to confuse people here on the list who don't
> know such techniques.

> Numeric precision still _IS_ a problem as I use these algorithms
> on several unix hosts (where there are such functions in long double)
> with much better results.

If you are using good computational forms, and thus getting results accurate
to 16 decimal places, I am a little curious as to why that is inadequate.
If you *aren't* getting results to 16 places, then I am still suspicious of
the computational forms.

> Someone actually removed them from current library ???
> Why ? Maybe because in ANSI they are definded as double precision
> functions, but couldn't it be possible to supply them whith different
> names, e.g. ld_sin() and wrap them with a #ifndef ANSI in math.h ?

For what it's worth, the latest draft of the emerging C9x standard specifies
float, double, and long double versions of all the math functions.

-Eric Rudd
rudd AT cyberoptics DOT com