\Header{glm.control}{Auxiliary for Controlling GLM Fitting}
\keyword{optimize}{glm.control}
\keyword{models}{glm.control}
\begin{Description}\relax
Auxiliary function as user interface for \code{\Link{glm}} fitting.
Typically only used when calling \code{\Link{glm}} or \code{\Link{glm.fit}}.\end{Description}
\begin{Usage}
\begin{verbatim}
glm.control(epsilon=1e-04, maxit=10, trace=FALSE)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{epsilon}] positive convergence tolerance \eqn{epsilon}{};
the iterations converge when \eqn{|dev - devold|/(|dev| + 0.1) < epsilon}{}.
\item[\code{maxit}] integer giving the maximal number of IWLS iterations.
\item[\code{trace}] logical indicating if output should be produced for each
iteration.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
If \code{epsilon} is small, it is also used as the tolerance for the
least squares solution.

When \code{trace} is true, calls to \code{\Link{cat}} produce the
output for each IWLS iteration. Hence, \code{\Link{options}(digits = *)}
can be used to increase the precision, see the example.\end{Details}
\begin{Value}
A list with the arguments as components.\end{Value}
\begin{SeeAlso}\relax
\code{\Link{glm.fit}}, the fitting procedure used by
\code{\Link{glm}}.\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
### A variation on  example(glm) :

## Annette Dobson's example ...
counts <- c(18,17,15,20,10,20,25,13,12)
outcome <- gl(3,1,9)
treatment <- gl(3,3)
oo <- options(digits = 12) # to see more when tracing :
glm.D93X <- glm(counts ~ outcome + treatment, family=poisson(),
                trace = TRUE, epsilon = 1e-15)
options(oo)
coef(glm.D93X) # the last two are closer to 0 than in ?glm's  glm.D93
\end{ExampleCode}
\end{Examples}

