| 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 |
plot type: see plot.default. |
ylab, log, ... |
labels and 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” expressions, 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)