On Fri, 12 Mar 2010, Prof Brian Ripley wrote:
On Wed, 10 Mar 2010, William Dunlap wrote:
This is very minor, but shouldn't log2(quote(1:10))
throw an error,the same as log() and other math functions
do? It looks like log2 and log10 evaluate a call object
instead of throwing a non-numeric-argument error. They
do object to non-call language objects, like expressions.
Yes, but the reason is complex. log2 and log10 first look for methods for
themselves, then for log, and the method dispatch code evaluates the argument
-- so it gets done twice. And because of some of the peculiarities of the
internal S4 dispatch code, it was hard enough to get to work at all.
The simplest solution seems to be to make log2() and log10() special
primitives (as log is):
And that does not work, due to S4 dispatch issues in package Rmpfr.
the alternative is to duplicate a version of the
logb() code in log2() and log10().
So I have done that.
> log2(quote(1:10))
[1] 0.000000 1.000000 1.584963 2.000000 2.321928 2.584963
[7] 2.807355 3.000000 3.169925 3.321928
> log(quote(1:10))
Error in log(quote(1:10)) : Non-numeric argument to mathematical
function
> sqrt(quote(1:10))
Error in sqrt(quote(1:10)) :
Non-numeric argument to mathematical function
> quote(1:10) ^ 2
Error in quote(1:10)^2 : non-numeric argument to binary operator
> 2 ^ quote(1:10)
Error in 2^quote(1:10) : non-numeric argument to binary operator
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
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--
Brian D. Ripley, rip...@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 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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--
Brian D. Ripley, rip...@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 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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