curve {graphics} | R Documentation |

Draws a curve corresponding to the given function or expression (in
`x`

) over the interval `[from,to]`

.

curve(expr, from, to, n = 101, add = FALSE, type = "l", ylab = NULL, log = NULL, xlim = NULL, ...) ## S3 method for class 'function': plot(x, from = 0, to = 1, xlim = NULL, ...)

`expr` |
an expression written as a function of `x` , or
alternatively the name of a function which will be plotted. |

`x` |
a ‘vectorizing’ numeric R function. |

`from,to` |
the range over which the function will be plotted. |

`n` |
integer; the number of x values at which to evaluate. |

`add` |
logical; if `TRUE` add to already existing plot. |

`xlim` |
numeric of length 2; if specified, it serves as default
for `c(from, to)` . |

`type, ylab, log, ...` |
graphical parameters can also be
specified as arguments.
`plot.function` passes all these to `curve` . |

The evaluation of `expr`

is at `n`

points equally spaced
over the range `[from, to]`

, possibly adapted to log scale. The
points determined in this way are then joined with straight lines.
`x(t)`

or `expr`

(with `x`

inside) must return a
numeric of the same length as the argument `t`

or `x`

.

If `add = TRUE`

, `c(from,to)`

default to `xlim`

which
defaults to the current x-limits. Further, `log`

is taken from the
current plot when `add`

is true.

This used to be a quick hack which now seems to serve a useful purpose, but can give bad results for functions which are not smooth.

For “expensive” `expr`

essions, you should use smarter tools.

`splinefun`

for spline interpolation, `lines`

.

op <- par(mfrow=c(2,2)) curve(x^3-3*x, -2, 2) curve(x^2-2, add = TRUE, col = "violet") plot(cos, xlim = c(-pi,3*pi), n = 1001, col = "blue") chippy <- function(x) sin(cos(x)*exp(-x/2)) curve(chippy, -8, 7, n=2001) curve(chippy, -8, -5) for(ll in c("","x","y","xy")) curve(log(1+x), 1,100, log=ll, sub=paste("log= '",ll,"'",sep="")) par(op)

[Package *graphics* version 2.1.0 Index]