plot::contour
-- generate
contour and implicit plotsplot::contour
([x, y, z], u = a..b, v =
c..d)
returns a contour plot of the surface defined by
(u,v) -> (x(u,v); y(u,v); z(u,v)) with (u,v) in
[a,b] x [c,d].
plot::contour([x, y, z], u = a..b, v = c..d <, option1,
option2...>)
x, y, z |
- | arithmetical expressions in u and
v |
u, v |
- | identifiers |
option1, option2, ... |
- | plot option(s) of the form option =
value , including the special plot options Colors and Contours (see below) |
an object of the domain type plot::Group
.
Colors |
- | either the list [Flat <, color>] ,
[Height <, fromColor, toColor>] or
[Curve,color1...] , where color ,
fromColor , toColor and color1 ...
are RGB color specifications, i.e., lists of three real numerical
values between 0 and 1. |
Contours |
- | either an integer greater than two, or a list of the form [r[1],...,r[n]] of real numerical values. |
plot
, plot2d
, plot::density
, plot::implicit
plot(...)
to display the contour plot created on
the screen.plot::contour
is a two-dimensional
object, and the plot options option1
,
option2
... must be valid plot options for two-dimensional
graphical objects. See plot2d
for details.Style = Attached
, the contour lines are
drawn with respect to the height of the surface which results in a
graphical object of dimension three.
Here, the plot options option1
, option2
...
must be valid plot options for three-dimensional graphical objects. See
plot3d
for details.
Note that scene options are not allowed! You may
give scene options as optional arguments for the function plot
, or use plot::Scene
to create an object
representing a graphical scene.
color
is red, the default values
for fromColor
and toColor
are yellow and red,
respectively.The following call returns an object representing a contour plot of the surface defined by (u,v) -> (u, v, exp(u*v) with (u,v) in [-1,1] x [-1,1]:
>> c:= plot::contour([x, y, exp(x*y)], x = -1..1, y = -1..1)
plot::Group()
To plot this object on the screen, call plot
:
>> plot(c)
With the option Style = Attached
, we get
the following three-dimensional contour plot of the same surface:
>> plot(plot::contour( [x, y, exp(x*y)], x = -1..1, y = -1..1, Style = Attached ))
If you want to color the contour plot with respect to the height of the surface, you may enter:
>> plot(plot::contour( [x, y, exp(x*y)], x = -1..1, y = -1..1, Colors=[Height] ))
Here, the default color values from red to yellow are used.
If you want to plot multiple contour plots in a single graphical scene, first create the desired contour plots, such as:
>> c1:= plot::contour( [x, y, sin(x*y)], x = -PI..PI, y = -PI..PI, Grid = [20,20] ): c2:= plot::contour( [x, y, x + 2*y], x= -PI..PI, y = -PI..PI, Colors=[Flat,RGB::Blue] ):
and collect them into a single graphical scene:
>> plot(c1, c2)
We plot the implicit function defined by (x^2 + y^2)^3 - (x^2 - y^2)^2 = 0:
>> plot(plot::contour( [x, y, (x^2 + y^2)^3 - (x^2 - y^2)^2], x = -1..1, y = -1..1, Contours=[0], Grid=[20,20] ))
Anyway, you may prefer the function plot::implicit
that is used to plot
graphs of implicit functions and therefore usually yields better
results:
>> plot(plot::implicit( (x^2 + y^2)^3 - (x^2 - y^2)^2, x = -1..1, y = -1..1 ))
plotlib::contourplot
plot::contour
is now part of the new plot library
plot
, and its calling
syntax and the return value were changed.