[R] problem with 'integrate'

[jim holtman]

?try

This will catch the error and let you take alternative action.

On 9/21/07, Dan Rabosky <dlr32 at cornell.edu> wrote:
>
> Hello -
>
> I am having a problem with the function 'integrate'.  I am running R
> on OSX (R 2.5.1).
>
> I am trying to suppress the error message when 'integrate' attempts
> to integrate across a parameter set giving a non-finite function
> value.  I'm using it in a MCMC / simulated annealing algorithm, and
> it is entirely possible that some parameter sets will give non-
> integrable functions.  I thought that the argument
>
> stop.on.error = FALSE
>
> would cause the function to return NA or at least not return an error
> (I can work around the situation where integrate returns garbage, but
> if it generates an error, it terminates my chain and all appears lost).
>
> This may not be necessary, but here is a simplification of an
> instance that generates the error.  If you send any B > 500 to
> "questionableFunction", the integration fails and returns an error
> message - even with stop.on.error = FALSE.  Is there any way I can
> work around this?  Perhaps there is something similar to
> "suppressWarnings()" that I might be able to use?
>
> questionableFunction <- function(B = 10)
> {
>        fx4 <- function(B, y, z){
>                1 + exp(B*y - B*z);
>         }
>
>        fx1 <- function(x, r0 = 0.12, k=-0.10, a=0.5, tshift=8.36){
>                (r0*exp(r0*t0 + (k/B)*log(fx4(B, t0, tshift)) - r0*x - (k/B)*log(fx4
> (B, x, tshift))))
>        }
>
>        integrate(fx1, 8.36, 10, stop.on.error = FALSE);
> }
>
>
>
> Thanks in advance for your help...
>
> Dan Rabosky
> Department of Ecology and Evolutionary Biology &
> Fuller Evolutionary Biology Program
> Cornell Lab of Ornithology
> Cornell University
> Ithaca, NY 14853-2701
>
>
>
>
>        [[alternative HTML version deleted]]
>
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>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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