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” 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)