[Maxima-discuss] draw2d parametric fails on a function defined by cases

[Eduardo O. <edu...@gm...>]

Hi all,

Try this:

  P(t) := [cos(t),sin(t)];
  draw2d(explicit(P(t)[1], t,0,10),
         explicit(P(t)[2], t,0,10));
  draw2d(parametric(P(t)[1], P(t)[2], t,0,10));

  P(t) := if t <= 6 then [t,4] else [6,10-t];
  draw2d(explicit(P(t)[1], t,0,10),
         explicit(P(t)[2], t,0,10));
  draw2d(parametric(P(t)[1], P(t)[2], t,0,10));

The first three "draw2d"s work perfectly, but the last one
yields this error:

  draw2d (parametric): non defined variable

I got the same error with the two versions of Maxima
that I have here, that are:

  Maxima branch_5_47_base_1348_g39c0ffa27 https://maxima.sourceforge.io
  using Lisp SBCL 2.1.1.debian

  Maxima 5.44.0 http://maxima.sourceforge.net
  using Lisp GNU Common Lisp (GCL) GCL 2.6.12

Is that documented? Is there a known workaround?

  Thanks in advance,
    Eduardo Ochs
    http://anggtwu.net/eev-maxima.html