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plot::Conformal(f(z), z =
) is a plot of the conformal function
over the complex interval
.
Call:
plot::Conformal(f, z = z1 .. z2, <a = amin .. amax>, Options)
Parameters:
|
f: |
An expression in z and the animation parameter, if present. Expected to be conformal in z. |
|
z: |
The independent variable: An identifier or indexed identifier. |
|
z1 .. z2: |
The (complex) range over which f should be plotted: z1 and z2 should be complex-valued expressions, possibly in the animation parameter. |
See Also:
plot, plot::copy, plot::Curve2d, plot::Function2d
Details:
plot::Conformal creates plots of (conformal) complex-valued functions of one complex variable. They are displayed by showing the image of a rectangular grid over an interval.
By default, the attribute LineColorType = Flat is set. All curves are displayed with the color given by the attribute LineColor (or Color for short).
When specifying the attribute LineColorType = Dichromatic, a color blend from LineColor to LineColor2 is used (“height coloring”).
When specifying the attribute LineColorType = Functional without specifying a LineColorFunction, all curves parametrized by the real part of the pre-image points are displayed with the flat color LineColor, whereas all curves parametrized by the imaginary part of the pre-image points are displayed with the flat color LineColor2.
A user defined LineColorFunction is a procedure (z, x, y, flag) -> RGB-color that will be called with complex floating point arguments z from the range of pre-images of the conformal function f, the real floating point values x = Re(f(z)), y = Im(f(z)), and the integer value flag which has the values 1 or 2. The flag value
determines the color of the curves parametrized by the real part of z, the flag value
determines the color of the curves parametrized by the imaginary part of z. The color function must return an RGB color, i.e., a list of 3 real floating point values between
and
. For example,
LineColorFunction = proc(z, x, y, flag)
begin
if flag = 1 then
return(RGB::Blue)
else
return(RGB::Red)
end_if;
end_proc
displays all curves parametrized by Re(z) in blue, while the orthogonal curves, parametrized by Im(z), are displayed in red.
See the examples in the documentation of RGB for another way of displaying complex functions.
Example 1
By plotting the identity function, we are presented the pre-image used by plot::Conformal:
plot(plot::Conformal(z, z = 0..1+I))

The important property of conformal functions, as far as plots are concerned, is that orthogonal lines are mapped onto curves meeting orthogonally:
plot(plot::Conformal(z^2, z = 0..1+I))

This property allows to visually detect overlapping regions (in some cases); in the following example this is the case in the left semi-plane:
plot(plot::Conformal(z^(3/2), z = -1-I..1+I))

Example 2
The default mesh may in some cases be too coarse:
plot(plot::Conformal(sin(z^2), z = 0..1+I))

There are at least three ways of improving this plot. Firstly, we can set Mesh to a higher value:
plot(plot::Conformal(sin(z^2), z = 0..1+I, Mesh = [50, 50]))

Another option would be to increase Submesh to get smoother, not more, lines:
plot(plot::Conformal(sin(z^2), z = 0..1+I, Submesh = [2, 2]))

Finally, we can also ask for an adaptive refinement of the submesh by setting AdaptiveMesh to some positive value:
plot(plot::Conformal(sin(z^2), z = 0..1+I, AdaptiveMesh = 2))

Example 3
Here is the image of the complex rectangle
,
under the map z
besselJ(0, z). We choose
as the second positive root of Im(besselJ(0, x + I)):
numeric::solve(Im(besselJ(0, x + I)), x = i .. i+1) $ i = 0..7
![]()
plot(plot::Conformal(besselJ(0, z), z = 0 .. 6.9934 + I,
Mesh = [31, 10]))


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