Draw Function Plots

Usage

curve(expr, from, to, n=101, add=FALSE, type="l", ylab = NULL, log=NULL, ...)
plot.function(fn, from=0, to=1, n=101, ...)

Arguments

expr an expression written as a function of x, or alternatively a function which will be plotted.
fn 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.
... graphical parameters can also be specified as arguments. plot.function passes all these to curve.

Description

Draws a curve corresponding to the given function or expression (in x) over the interval [from,to].

Details

The evaluation of expr is at n points equally spaced over the range [from, to]. The points determined in this way are then joined with straight lines. fn(x) or expr (with x inside) must return a numeric of the same length as x.

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

Value

NULL. For ``expensive'' expressions, you should use smarter tools.

See Also

splinefun for spline interpolation, lines.

Examples

par(mfrow=c(2,2))
curve(x^3-3*x, -2, 2)
curve(x^2-2, add = TRUE, col = "violet")

curve(sin, -pi, 3*pi)
plot(cos)
chippy <- function(x) sin(cos(x)*exp(-x/2))
curve(chippy, -8, 7, n=2001)

for(ll in c("","x","y","xy"))
   curve(log(1+x), 1,100, log=ll, sub=paste("log=",ll))

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