Re: [R] 0^0 computation in R : Why it is defined 1 in R ?
On 26/05/2014 13:16, ritwi...@isical.ac.in wrote:
Dear R helpers,
today I found something interesting in R. 0^0 gives value 1 in R. But it
is undefined in mathematics. During debugging a R code, I found it and it
effects my program severely. So my question is why it is defined 1 in R?
Is there any particular reason or its a bug in the R software?
Try reading the help:
Users are sometimes surprised by the value returned, for example
why ‘(-8)^(1/3)’ is ‘NaN’. For double inputs, R makes use of IEC
60559 arithmetic on all platforms, together with the C system
function ‘pow’ for the ‘^’ operator. The relevant standards
define the result in many corner cases. In particular, the result
in the example above is mandated by the C99 standard. On many
Unix-alike systems the command ‘man pow’ gives details of the
values in a large number of corner cases.
See §F9.4.4 of the C99 standard.
Here is one demo:
*
ff=function(u){
return( x^0 * u)
}
x=0
zz=integrate(ff,lower=0,upper=1)$value
zz
source('~/.active-rstudio-document')
zz
[1] 0.5
*
Looking forward to hear any response.
Regards,
Ritwik Bhattacharya
Indian Statistical Institute Kolkata
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--
Brian D. Ripley, rip...@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UKFax: +44 1865 272595
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and provide commented, minimal, self-contained, reproducible code.
Re: [R] 0^0 computation in R : Why it is defined 1 in R ?
You might find searching the web on this topic educational. Consider [1] and
[2], for example.
I doubt this will be changing, so you should do your exponentiation in a
function that handles your special case.
By the way, as nice as RStudio might be, it is not R... it USES R. Examples
like yours won't run as-is in vanilla R so are not really reproducible for
(probably most) readers of this list. Please (re-)read the Posting Guide.
[1] http://mathforum.org/dr.math/faq/faq.0.to.0.power.html
[2]
http://www.askamathematician.com/2010/12/q-what-does-00-zero-raised-to-the-zeroth-power-equal-why-do-mathematicians-and-high-school-teachers-disagree/
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On May 26, 2014 5:16:21 AM PDT, ritwi...@isical.ac.in wrote:
Dear R helpers,
today I found something interesting in R. 0^0 gives value 1 in R. But
it
is undefined in mathematics. During debugging a R code, I found it and
it
effects my program severely. So my question is why it is defined 1 in
R?
Is there any particular reason or its a bug in the R software?
Here is one demo:
*
ff=function(u){
return( x^0 * u)
}
x=0
zz=integrate(ff,lower=0,upper=1)$value
zz
source('~/.active-rstudio-document')
zz
[1] 0.5
*
Looking forward to hear any response.
Regards,
Ritwik Bhattacharya
Indian Statistical Institute Kolkata
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] 0^0 computation in R : Why it is defined 1 in R ?
On May 26, 2014, at 9:42 AM, Prof Brian Ripley wrote:
On 26/05/2014 13:16, ritwi...@isical.ac.in wrote:
Dear R helpers,
today I found something interesting in R. 0^0 gives value 1 in R. But it
is undefined in mathematics. During debugging a R code, I found it and it
effects my program severely. So my question is why it is defined 1 in R?
Is there any particular reason or its a bug in the R software?
Try reading the help:
Users are sometimes surprised by the value returned, for example
why ‘(-8)^(1/3)’ is ‘NaN’. For double inputs, R makes use of IEC
60559 arithmetic on all platforms, together with the C system
function ‘pow’ for the ‘^’ operator. The relevant standards
define the result in many corner cases. In particular, the result
in the example above is mandated by the C99 standard. On many
Unix-alike systems the command ‘man pow’ gives details of the
values in a large number of corner cases.
See §F9.4.4 of the C99 standard.
A related questi0n is why NaN^0 == 0 returns TRUE:
http://stackoverflow.com/questions/17863619/why-does-nan0-1/17864651
--
David.
Here is one demo:
*
ff=function(u){
return( x^0 * u)
}
x=0
zz=integrate(ff,lower=0,upper=1)$value
zz
source('~/.active-rstudio-document')
zz
[1] 0.5
*
Looking forward to hear any response.
Regards,
Ritwik Bhattacharya
Indian Statistical Institute Kolkata
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
PLEASE do
David Winsemius
Alameda, CA, USA
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
