R help - Sep 2008 - lower and upper limits in integrate as vectors

Dear R useRs,

i try to integrate the following function for many values

"integrand" <- function(z)
{
  return(z * z)
}

i do this with a for-loop

for(i in 2:4)
{
  z <- integrate(integrand, i-1, i)$value
  cat("z", z, "\n")
}

to speed up the computation for many values i tried vectors
in integrate to do this.

vec1<-1:3
vec2<-2:4

integrate(Vectorize(integrand), vec1, vec2)$value

but here it seems the integration works only for the first values of 
vec1 and vec2.

If you have any advice how i can to this computations with vectors or 
something like that, i would be very thankful,

best regards

Andreas

Hi,

I think you want to Vectorize integrate(), not integrand(). Here's a  
way using mapply,
> integrand <- function(z)
> {
> return(z * z)
> }
>
> vec1<-1:3
> vec2<-2:4
>
> mapply(integrate, lower=vec1, upper=vec2, MoreArgs=list(f=integrand) )
baptiste

On 20 Sep 2008, at 13:08, Andreas Wittmann wrote:
> Dear R useRs,
>
> i try to integrate the following function for many values
>
> "integrand" <- function(z)
> {
> return(z * z)
> }
>
> i do this with a for-loop
>
> for(i in 2:4)
> {
> z <- integrate(integrand, i-1, i)$value
> cat("z", z, "\n")
> }
>
> to speed up the computation for many values i tried vectors
> in integrate to do this.
>
> vec1<-1:3
> vec2<-2:4
>
> integrate(Vectorize(integrand), vec1, vec2)$value
>
> but here it seems the integration works only for the first values of  
> vec1 and vec2.
>
> If you have any advice how i can to this computations with vectors  
> or something like that, i would be very thankful,
>
> best regards
>
> Andreas
>
> ______________________________________________
> R-help at 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.
_____________________________

Baptiste Augui?

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag