Re: [R] Reduced Numerical Precision in 1.2.x?

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Subject: Re: [R] Reduced Numerical Precision in 1.2.x?
From: Prof Brian Ripley (ripley@stats.ox.ac.uk)
Date: Thu 01 Feb 2001 - 00:13:27 EST 

Message-ID: <Pine.GSO.4.31.0101311406070.4294-100000@toucan.stats>

On Wed, 31 Jan 2001 Jeff_Lischer@mksinst.com wrote:

> I have noticed a definite loss of numerical precision going from 1.1.1 to
> 1.2.x under both Windows 98 and NT4 on x86 architecture.

Did you use exactly the same compiler? If you used the pre-compiled
versions you are almost certainly attributing this to the wrong cause,
so please compile it yourself before making such statements, and do
check that you have read the CHANGES file.

> I noticed the
> difference when using the abcnon() function in the bootstrap package, but I
> think you could see the problem in any routine that involves subtracting
> relatively large numbers from each other.

Any badly-written routine, therefore? Rounding error is a fact of life,
and I think your code is relying on its absence.

I find the code in package boot to be a great deal more trustworthy than
that in bootstrap. 

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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