NAME
cplxview - module to visualize the graphs of complex func-
tions.
DESCRIPTION
Purpose: to allow the user to examine complex functions.
Features: functions typed into the function panel are
interpreted via a fexpr, a fast expression evaluator written
at the Geometry Center. The domain of the function may be
specified in a variety of ways, including user defined coor-
dinates. Since the graphs of complex functions live in C^2,
this viewer makes use of the n-dimensional viewing capabili-
ties of geomview (see ndview).
What you see at start-up: the graph of the complex exponen-
tial function, seen from four vantage points. At the top of
the windows, there is a label similar to "cluster1:1_2_4".
The last three numbers correspond to the directions visible
in the window. In this case, 1_2_4 corresponds to the real
part of z, the imaginary part of z, and the imaginary part
of the function of z. The color corresponds to the dimen-
sion that has been projected out, in this example the real
part of the function of z.
How-to-use-it: This section will describe the meaning
or use of the buttons and inputs, organized by what is shown
on the main panel.
Function: please type the function you would like to graph
in this input. The parser understands parenthesis, standard
functions like sin and log, and various constants, namely i,
e, and pi. To get exponentials, use the power ("pow") func-
tion, as in "pow(2,z)". When you are done typing in the new
function, hit return. If the parser understands what you
wrote, you will see a message saying "new function
installed" in the message window.
Domain: this part of the panel determined the domain over
which the function is to be graphed. The meaning of each of
the four numbers is displayed to its left, which changes if
you change the coordinate system. Use the arrows to modify
these numbers. If you would like more or less precise con-
trol than that afforded in this system, you might incor-
porate your wishes into the function you are graphing. For
example, if you wish to graph f(z) = log(z) very near the
origin, you may instead wish to use f(z) = log(z/1000).
When modifying the domain, advanced users may wish to turn
off normalization in geomview.
Range: pressing this button will give you the range panel,
on which you can specify that you wish to see the (three
dimensional) graph of the real part of the function, the
(three dimensional) graph of the imaginary part of the func-
tion, or the actual four-dimensional graph, as viewer
through the n-dimensional viewer.
Meshsize: you can modify how fine the mesh used to show the
function is. Note that this is a regular mesh, which
doesn't try to avoid singularities. Note also that the
fineness of the mesh (along with the domain) is remembered
as you change coordinate systems.
Coordtype: this button brings up the panel for specifying
the coordinate system you wish to use for determining the
domain to be graphed. There are three choices: rectangular,
polar, and user-defined coordinates. The user-defined coor-
dinates mean that z is defined in terms s and t, which are
in turn functions of u and v. The same parsing mechanism is
applied to these functions as to the function to be graphed.
At the right on the coordtype panel is the explanation of
what z is assigned to. Advanced users may use all the sym-
bols listed there (x, y, r, theta, s, and t) in the main
function window but are advised that there may be unexpected
consequences if they are used in the "wrong" coordinate sys-
tem context.
Sliders: users may also make use of two constants "a" and
"b" which are attached to sliders, if they so desire. These
constants can be inserted into a function just as one might
expect, for example, one could have a function "a*sin(z+b)",
or "pow(z,a+i*b)". The default setting of the user defined
coordinates uses these sliders to determine a rectangular
domain whose size depends on the slider values.
Help: the help button calls up this panel. More informa-
tion can be found in the manual pages, and comments are
appreciated.
AUTHORS
Olaf Holt and Nils McCarthy
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