[R] problem with integrate() - correction

[Frede Aakmann Tøgersen]

Well why not do it symbolically, e.g.

int(a*x^b,x) = \frac{a}{b+1}x^{b+1}

and integrating this again gives

\frac{a}{(b+1)(b+2)}x^{b+2},

of course for resonable values of a and b such that things are well defined.

But if you follow the link

https://stat.ethz.ch/pipermail/r-help/2005-January/064026.html

you may come to this solution:


ip <- function(x) 1240 * x^(-0.88)

iip <- function(x){
  res <- rep(NA,length(x))
  for (i in seq(along=x))        
    res[i] <- integrate(ip, x[i] - 0.045, x[i] + 0.045)$value
  return(res)
}

f <- integrate(iip, 10, 100)

which may not be an effective way to do it.


Med venlig hilsen
Frede Aakmann Tøgersen
 

 

> -----Oprindelig meddelelse-----
> Fra: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] På vegne af Rainer M Krug
> Sendt: 22. juni 2006 14:03
> Til: rkrug at sun.ac.za
> Cc: R help list
> Emne: [R] problem with integrate() - correction
> 
> Sorry
> 
> should read:
> 
> ip <- function(x) 1240 * x^(-0.88)
> 
> 
> Rainer M Krug wrote:
> > Hi
> > 
> > System:
> > Linux, SuSE 10
> > R 2.3.0
> > 
> > I try to do the following
> > 
> >> ip <- function(x) 1240*dip(x, 0.88)
> >> iip <- function(x) integrate(ip, x - 0.045, x + 0.045)$value f <- 
> >> integrate(iip, 10, 100)
> > Error in integrate(iip, 10, 100) : evaluation of function gave a 
> > result of wrong length
> > 
> > How can I solve this?
> > 
> > Thanks
> > 
> > Rainer
> > 
> > 
> > 
> 
> 
> --
> Rainer M. Krug, Dipl. Phys. (Germany), MSc Conservation Biology (UCT)
> 
> Department of Conservation Ecology and Entomology University 
> of Stellenbosch Matieland 7602 South Africa
> 
> Tel:		+27 - (0)72 808 2975 (w)
> Fax:		+27 - (0)21 808 3304
> Cell:		+27 - (0)83 9479 042
> 
> email:	RKrug at sun.ac.za
>       	Rainer at krugs.de
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
>