[R] Integrate a 1-variable function with 1 parameter (Jose L. Romero)

[jose romero]

To Ravi Varadhan and Peter Dalgaard:

Infinite thanks for your help and suggestions- they were very instructive, as i have still to learn on the appropriate use of the apply family of functions.

jlrp


--- On Wed, 8/27/08, Ravi Varadhan <RVaradhan at jhmi.edu> wrote:

> From: Ravi Varadhan <RVaradhan at jhmi.edu>
> Subject: RE: [R] Integrate a 1-variable function with 1 parameter (Jose L. Romero)
> To: jlaurentum at yahoo.com, r-help at r-project.org
> Date: Wednesday, August 27, 2008, 2:42 PM
> Here is one way:
> 
> integrand <- function (t, x) {
> 	exp(-2*t)*(2*t)^x/(10*factorial(x))
> }
> 
> x <- 0:44
> ans <- sapply(x, function(x) integrate(integrand,
> lower=0, upper=10, x=x))
> cbind(x=x, integral=unlist(ans[1,]),
> abs.error=unlist(ans[2,]))
>  
> 
> Ravi.
> 
> ----------------------------------------------------------------------------
> -------
> 
> Ravi Varadhan, Ph.D.
> 
> Assistant Professor, The Center on Aging and Health
> 
> Division of Geriatric Medicine and Gerontology 
> 
> Johns Hopkins University
> 
> Ph: (410) 502-2619
> 
> Fax: (410) 614-9625
> 
> Email: rvaradhan at jhmi.edu
> 
> Webpage: 
> http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html
> 
>  
> 
> ----------------------------------------------------------------------------
> --------
> 
> 
> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] On
> Behalf Of jose romero
> Sent: Wednesday, August 27, 2008 10:24 AM
> To: r-help at r-project.org
> Subject: [R] Integrate a 1-variable function with 1
> parameter (Jose L.
> Romero)
> 
> Hey fellas:
> 
> I would like to integrate the following function:
> 
> integrand <- function (x,t) {
> 	exp(-2*t)*(2*t)^x/(10*factorial(x))
> }
> 
> with respect to the t variable, from 0 to 10.
> The variable x here works as a parameter: I would like to
> integrate the said
> function for each value of x in 0,1,..,44.
> 
> I have tried Vectorize to no avail.
> 
> Thanks in advance,
> jose romero
> 
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