Description Usage Arguments The graph of a function Parametric equations Images of curves See Also Examples
This function takes a description of a curve and creates an object displaying the curve, and optionally
it's behavior throughout iterations of the system. Functions can be provided as expressions of x
,
for graphing curves, or t
, for parametric curves.
The curve is defined either by the graph of a single function or a pair of parametric
equations. By default, rendered with the lines
function.
1 2 3 |
fun |
A function. If |
yfun |
The y-equation of the parameteric equations. See sections describing parametric equations for more info. |
col |
The color of the original curve, as a string. |
image |
A single color as a string, or a vector of colors as a string. See details for more information. |
lwd |
Line width expressed as a double. Only used if |
n |
The number of points that will be calculated.
Defaults to the dsrange's |
iters |
Determines the number of iterations of the function when making a color gradient.
Use |
crop |
If |
tstart |
Only used for parametric curves. The minimum input for both functions. Default 0. |
tend |
Only used for parametric curves. The maximum input for the functions. Default 1. |
discretize |
Set |
xlim |
Only used for the graph of a function. Determines the range of x values for which the function is plotted. Defaults to the x limits of the model's dsrange. |
... |
Further graphical parameters passed to |
If the parameter yfun
is not provided, then dscurve
contains
the curve of points (x,fun(x)). The inputs to fun
are n
points between the maximum
dsrange
's x limits, but can be overwritten with the xlim
parameter.
fun
can either be any function of a single parameter, or an expression with exactly x
as the free variable.
If the parameter fun
and yfun
are both provided,
dscurve
contains the parametric curve described by the functions. The function is
calculated at n
points ranging from tmin
to tmax
.
fun
and yfun
can either be any function of a single parameter, or an expression with exactly t
as the free variable.
The dscurve
object begins with an initial curve. Images of the curve may be displayed in three ways.
If the image
parameter is a single color and iters
is not set, then dscurve
will calculate and display
the image of the curve under the model's function in that color.
If the image
parameter is a vector of k colors, then dscurve
calculates and
displays k successive images of the curve using those colors.
The string "NA" may be used to avoid displaying an iteration.
If the image
parameter is a single color and iters
is defined, then iters
successive images are displayed, using a gradient between col
and image
.
In most cases, rather than specifying col
and image
separately, they may be
combined into a single vector.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | library(dsmodels)
fun <- function(X,Y) {
list(
X/exp(Y),
Y/exp(X)
)
}
model <- dsmodel(fun, title = "Points on a One-Dimensional Curve")
range <- dsrange(-2:2,-2:2, discretize = 0.5)
# Add the graph of a function and its image in blue.
graphcrv <- dscurve(function(x) x^2,
col = "orange",
image = "blue",
discretize = TRUE,
xlim = c(-2,2))
model + range + graphcrv
# Add the graph of expression of x.
model + dscurve(x^2+1, col="yellow")
# Create a parametric curve with image iterations red then green.
paramcrv <- dscurve(function(t) t^2, function(t) t,
image = c("red", "green"),
tstart = -2, tend = 2)
dsmodel(fun, "A Parametric Curve and Iterations of that Curve") +
dsrange(-2:2, -2:2, discretize = 0.5) +
# A parametic curve defined by expressions of t.
paramcrv + dscurve(4*t-2,4*t-2,col="blue")
|
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