\Header{options}{Options Settings}
\alias{.Options}{options}
\keyword{environment}{options}
\keyword{print}{options}
\begin{Usage}
\begin{verbatim}
options(...)
.Options
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\texttt{...}] any options can be defined, using \texttt{name = value}.
However, only the ones below are used in ``base \R''.

Further, \texttt{options('name') == options()['name']}, see the example.

\item[\texttt{prompt}] a string, used for \R's prompt; should usually end in a
blank (\texttt{" "}).
\item[\texttt{continue}] a string setting the prompt used for lines which continue
over one line.
\item[\texttt{width}] controls the number of characters on a line. You may
want to change this if you resize the window that \R\ is running in.
\item[\texttt{digits}] controls the number of digits to print when printing
numeric values. It is a suggestion only.
\item[\texttt{editor}] sets the default text editor, e.g., for \texttt{\Link{edit}}.
\item[\texttt{browser}] default HTML browser used by \texttt{\Link{help.start}()}.
\item[\texttt{contrasts}] the default \texttt{\Link{contrasts}} used in model
fitting such as with \texttt{\Link{aov}} or \texttt{\Link{lm}}.
\item[\texttt{expressions}] sets a limit on the number of nested expressions that
will be evaluated.   This is especially important on the Macintosh
since stack overflow is likely if this is set too high.
\item[\texttt{na.action}] the name of a function for treating missing values
(\texttt{\Link{NA}}'s) for certain situations.
\item[\texttt{pager}] the (standalone) program used for displaying ASCII files on
\R's console.  Defaults to \file{\$RHOME/bin/pager}.
\item[\texttt{papersize}] the paper format used for graphics printing; currently
\bold{read-only}, set by environment variable R\_PAPERSIZE, or in
\file{config.site}.
\item[\texttt{printcmd}] the command used for graphics printing; currently
\bold{read-only}, set by environment variable R\_PRINTCMD, or in
\file{config.site}.
\item[\texttt{show.signif.stars, show.coef.Pvalues}] logical, affecting P value
printing, see \texttt{\Link{print.coefmat}}.
\item[\texttt{ts.eps}] the relative tolerance for certain time series
(\texttt{\Link{ts}}) computations.
\end{ldescription}
\end{Arguments}
\begin{Description}
\texttt{options} allows the user to set and examine a variety of global
``options'' which affect the way in which \R\ computes and displays
its results.\end{Description}
\begin{Details}
Invoking \texttt{options()} with no arguments returns a list with the
current values of the options.
\texttt{.Options} is another way to access this list \bold{``read only''}.

Accessing current options, usually will work with \texttt{.Options\$width}
(e.g.), rather than \texttt{options("width")} which is a \emph{list} of
length one.\end{Details}
\begin{Value}
A list (in any case) with the previous values of the options changed,
or all options when no arguments were given.\end{Value}
\begin{Examples}
\begin{ExampleCode}
options() # printing all current options
op <- options(); str(op) # nicer printing

# .Options is the same:
all(sapply(1:length(op), function(i) all(.Options[[i]] == op[[i]])))

options('width')[[1]] == options()$width # the latter needs more memory
options(digits=20)
pi

# set the editor, and save previous value
old.o <- options(editor="nedit")
old.o

options(op)	# reset (all) initial options
options('digits')
\end{ExampleCode}
\end{Examples}

