[Maxima] plotting numeric functions

James Limbouris limboj01 at student.uwa.edu.au
Mon May 24 02:15:50 CDT 2010


Hi all,

Something I have had trouble with for quite some time is the plotting of numeric functions.
Say you have a very complicated function f(x), that will go away and not come back if you attempt
to evaluate it symbolically. Maybe its definition contains a bunch of nested noun form functions
for instance. Now say it evaluates instantly as:

f(x), x=3, numer, keepfloat;

But if you try to plot it:

wxplot2d(f(x), [x, 1, 3]), numer;

it will go away and not come back. Now if it were just a numeric function that required that its
arguments be floats, you could fix this by using:

wxplot2d('f(x), [x, 1, 3]), numer;

The quote would suppress evaluation of f(x) until its arguments were substituted, and it would work.
But for hideous analytic functions, I have had no luck with any combination of quotes, or hacks of the form:

hack(expression, x) :=
block(
      if not numberp(x) then return('hack(expression, x)),
      return(ev(expression, expand, nouns, numer, keepfloat))
)$

or anything else I can think of.

I know you can do discrete plots in 2D, but plot3D has no discretes, and draw3d's mesh function gives incorrect axis values.
Does anyone know a way around this? Can any developers see a why to fix this behavior? Any help advice would be much appreciated.

Thanks,
James


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