| curve {graphics} | R Documentation |
Draws a curve corresponding to the given function or, for
curve() also an expression (in x) over the interval
[from,to].
curve(expr, from = NULL, to = NULL, n = 101, add = FALSE,
type = "l", ylab = NULL, log = NULL, xlim = NULL, ...)
## S3 method for class 'function':
plot(x, y = 0, to = 1, from = y, 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. |
y |
alias for from for compatibility with plot() |
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.
For curve(), if either of from or to is
NULL, it defaults to the corresponding element of xlim,
and xlim defaults to the x-limits of the current plot.
For plot(<function>, ..), the defaults for (from,to) are
(0,1).
log is taken from
the current plot only when add is true, and otherwise
defaults to "" indicating linear scales on both axes.
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-to-compute expressions, you should use smarter tools.
splinefun for spline interpolation, lines.
plot(qnorm)
plot(qlogis, main = "The Inverse Logit : qlogis()")
abline(h=0, v=0:2/2, lty=3, col="gray")
curve(sin, -2*pi, 2*pi)
curve(tan, main = "curve(tan) --> same x-scale as previous plot")
op <- par(mfrow=c(2,2))
curve(x^3-3*x, -2, 2)
curve(x^2-2, add = TRUE, col = "violet")
## simple and sophisticated, quite similar:
plot(cos, -pi, 3*pi)
plot(cos, xlim = c(-pi,3*pi), n = 1001, col = "blue", add=TRUE)
chippy <- function(x) sin(cos(x)*exp(-x/2))
curve(chippy, -8, 7, n=2001)
plot (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)