From: ripley@stats.ox.ac.uk
Date: Sat 15 Jun 2002 - 16:55:15 EST
Message-id: <Pine.LNX.4.31.0206150753520.23922-100000@gannet.stats>
On Sat, 15 Jun 2002, Faheem Mitha wrote:
>
> Dear R People,
>
> I getting some curious behaviour with the integrate function. Consider the
> function
>
> foo <- function(x)
> {
> if(x==0)
> 4
> else
> 0
> }
>
> I get the error
>
> > integrate(foo,0,1)
> Error in integrate(foo, 0, 1) : evaluation of function gave a result of
> wrong length
>
> But now consider
>
> foo <- function(x)
> {
> ifelse(x==0,4,0)
> }
>
> > integrate(foo,0,1)
> 0 with absolute error < 0
>
> I am guessing this may have something to do with types/classes, but I
> don't see exactly what. I would be happy to be enlightened.
>
> Yhe help page says the function must be
>
> "f An R function taking a numeric first argument and returning a numeric
> vector the same length."
>
> But I don't see any difference in what these two return. In both cases it
> is NULL.
No, in the first case it is vector of length 1, and in the second a vector
of the length of x. Did you actually try it? Please do to convince
yourself.
S functions return the value of their last statement.
-- 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-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
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