On Wed, 2010-05-12 at 21:18 +0200, Krzysztof Miernik wrote:
> Since Maxima update to 5.21.1 I am not able to plot 3D parametric
> function which depends on single parameter only. Example is a helix:
>
> plot3d([t,sin(t),cos(t)],[t,0,30],[x,-1,1]);
> plot3d: wrong number of variables: [t]. There should be two
> -- an error. To debug this try: debugmode(true);
>
> This plot would work fine with previous version of Maxima.
Hi,
at least with 5.19, 5.20 and 5.21 which are the 3 versions I have
installed, it fails. In which version did it use to work?
I'm sorry I was not aware that older versions of plot3d were able to
plot 3D curves and not just surfaces.
I will try to introduce that feature soon.
In the mean time, you can fool plot3d into thinking that it has
an expression with two parameters, instead of just one:
plot3d([ signum(abs(x))*t, sin(t), cos(t)], [t,0,30], [x,-1,1]);
While we are discussing this, I think that the old behavior you
describe:
plot3d([t, sin(t), cos(t)], [t,0,30], [u,-1,1]);
should give an error ("unknown option u"), while:
plot3d([t, sin(t), cos(t)], [t,0,30], [x,-1,1]);
should interpret [x,-1,1] not as a parameter but simply as the option
that limits the x axis. It should also be enough to simply write:
plot3d([t, sin(t), cos(t)], [t,0,30]);
Regards,
Jaime