## Plot Annotation

## Usage

    title(main = "", sub = "", xlab = "", ylab = "", ...)

## Arguments

`main` | The main title (on top) using font and size (character expansion) `par("font.main")` and color `par("col.main")`.
`sub` | Sub-title (at bottom) using font and size `par("font.sub")` and color `par("col.sub")`.
`xlab` | X axis label using font and character expansion `par("font.axis")` and color `par("col.axis")`.
`ylab` | Y axis label, same font attributes as `xlab`.
`...` | further graphical parameters (from `par`).

## Description

This function can be used to add labels to a plot. Its first four principal arguments can also be used as arguments in most high-level plotting functions. They must be of type `character` or `expression`. In the latter case, quite a bit of mathematical notation is available such as sub- and superscripts, greek letters, fractions, etc.

## See Also

`mtext`, `text`.

## Examples

    plot(cars, main = "")
    title(main = "Stopping Distance versus Speed")

    x <- seq(-4, 4, len = 101)
    y <- cbind(sin(x), cos(x))
    matplot(x, y, type = "l", xaxt = "n",
            main = expression(paste(plain(sin) * phi, "  and  ",
                                    plain(cos) * phi)),
    	ylab = expression("sin" * phi, "cos" * phi),    # only 1st is taken
    	xlab = expression(paste("Phase Angle ", phi)),
    	col.main = "blue")
    axis(1, at = c(-pi, -pi/2, 0, pi/2, pi),
         lab = expression(-pi, -pi/2, 0, pi/2, pi))
    abline(h = 0, v = pi/2 * c(-1,1), lty = 2, lwd = .1, col = "gray70")

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