Plotting a function in Maxima

Question

I am trying to plot two functions (two differential equations) in Maxima using the wxdrawdf() function, my code is wrong because I get the following error when I try running it

2D graphic object not recognized, *

The two functions I am trying to plot are (x^2-4)(y+2) and (x-1)(y^2-9) My implementation of the wxdrawf() is

load(drawdf);
wxdrawdf((x^2-4)*(y+2),(x-1)*(y^2-9),field_arrow=true, [trajectory_at, 1,-2], [trajectory_at, 2,3], [trajectory_at, 2,-3], [trajectory_at, -2,3], [trajectory_at, -2,-3] )$

Answer 1

I think the problem is that the two expressions which you put first in the call to wxdrawdf must be a list of two elements, not two separate arguments. Try this:

wxdrawdf ([(x^2-4)*(y+2), (x-1)*(y^2-9)], ...);

putting any other arguments in place of ... there.

The error message is obscure; the message should help the user figure out what's wrong. If you are interested, maybe you can report a bug to the Maxima bug tracker: https://sourceforge.net/p/maxima/bugs/