# [R] Capture of iterative integration output

Terry W. Schulz terrywschulz at comcast.net
Sun Aug 27 00:42:17 CEST 2006

```Hello,

I am a novice R user and am having difficulty retrieving  the values
from 21 iterations of the R function integrate.
The only way I have found is to do a write.table and then a read.table
as shown in the code below.  I would rather capture the 21 values inside
the braces ( sapply might work, but I can't set it up without getting an
error in function) so I could compute the negative log-likelihood inside
the braces.  My goal is to then use optim to find the best fitting mu
and sigma.  In the code that follows mu and sigma are given, but
normally they would not be known.

Any help on y\$value capture would be appreciated.  I would be ecstatic
for help on implementation of the optim function using finite
differences for the following code.

By the way in case anyone is interested function(x) is the
Poisson-lognormal pdf.

attach(q)
V <- c(volume)
c <- c(count)
n <- length(count)
mu <- -8.202900475
sigma <- 1.609437912
for(i in c(1:n))
{
integrand <- function(x)
{(x*V[[i]])^c[[i]]*exp(-x*V[[i]])/factorial(c[[i]])*0.3989422804014327/
(x*sigma)*exp(-.5*((log(x)-mu)/sigma)^2)}
y <- integrate(integrand, lower = 0, upper = Inf)
write.table(y[],file="c:/Bayes/PLNA3-1.out",append=TRUE,
quote=FALSE,row.names=FALSE,col.names=FALSE)
}
z <- c(z)
LL <- log(c(z\$V1))
#negative Log-Likelihood
print(-sum(LL),digits=6)
file.remove("c:/Bayes/PLNA3-1.out")

--
Terry W. Schulz
Applied Statistician
1218 Pomegranate Lane
Golden, CO 80401
USA

terrywschulz at comcast.net
(303) 526-1461

```