\Header{units}{Graphical Units}
\alias{cm}{units}
\alias{xinch}{units}
\alias{xyinch}{units}
\alias{yinch}{units}
\keyword{dplot}{units}
\begin{Description}\relax
\code{xinch} and \code{yinch} convert the specified number of inches
given as their arguments into the correct units for plotting with
graphics functions.  Usually, this only makes sense when normal
coordinates are used, i.e., \emph{no} \code{log} scale (see the
\code{log} argument to \code{\Link{par}}).

\code{xyinch} does the same for a pair of numbers \code{xy},
simultaneously.

\code{cm} translates inches in to cm (centimeters).
\end{Description}
\begin{Usage}
\begin{verbatim}
xinch(x = 1, warn.log = TRUE)
yinch(y = 1, warn.log = TRUE)
xyinch(xy = 1, warn.log = TRUE)
cm(x)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x,y}] numeric vector
\item[\code{xy}] numeric of length 1 or 2.
\item[\code{warn.log}] logical; if \code{TRUE}, a warning is printed in case
of active log scale.
\end{ldescription}
\end{Arguments}
\begin{Examples}
\begin{ExampleCode}
all(c(xinch(),yinch()) == xyinch()) # TRUE
xyinch()
xyinch #- to see that is really   delta{"usr"} / "pin"

cm(1)# = 2.54

## plot labels offset 0.12 inches to the right
## of plotted symbols in a plot
data(mtcars)
with(mtcars, {
    plot(mpg, disp, pch=19, main= "Motor Trend Cars")
    text(mpg + xinch(0.12), disp, row.names(mtcars),
         adj = 0, cex = .7, col = 'blue')
    })
\end{ExampleCode}
\end{Examples}

