curve alias parametric and a sphere should be a sphere

Hallo Wolfgang,

Sometimes, the Maxima syntax is hard to understand by young students,
and if you are using Maxima as a pedagogical tool, you don't want to
transform a mathematics class in a maxima class.

In my case, I usually write a mac package with wrappers for more
elaborated function calls, so that students don't need to write a lot of
code; something like


load(draw)$
paint(line):= draw3d( apply(parametric,append(line,[t,-2,2])))$


When students start Maxima, they only need to type

load("path_to_mac_file");
paint([2,3,0]+t*[1,-2,1]);

to see a piece of line.

Even easier, you can write in your Maxima initialization file
(maxima-init.mac):

load("path_to_mac_file")$

so that everytime they start Maxima, your mac file will be automatically
loaded.


> 
> working with package DRAW.lisp I have 3 questions.
> 
> [1]
> I learned form Mario the construction (%i2):
> 
> (%i1)  line : [2,3,0]+t*[1,-2,1]$
> (%i2)  draw3d( apply(parametric,append(line,[t,-2,2])));
> 
> I abstracted this construction to
> 
> (%i3)  Line(L,T) := apply(parametric,append(L,T));
> (%i4)  draw3d(Line(line,[t,-2,2]));
> 
> ok. But I don't like to do this definition everytime I use draw ..
> ok, I could write all private function definitions in a seperate file and load it
> everytime,
> but better: how to formulate (%i3) in Lisp in order to put it in DRAW.lisp? 
> 
> [2]
> 
> I prefer the identifier 'curve'   to 'parametric'
> and      the identifier 'surface' to 'parametric_surface'.
> So currently I do everytime:
> 
> (%i5)  alias(curve,parametric,  surface,parametric_surface);
> (%i6)  draw2d(curve(cos(t),sin(t),t,0,2*%pi))$
> 

I'd write this in a separate file, as explained above. You could make
use of German words, if you wish so.



> how to formulate (%i5) in Lisp in order to put it in DRAW.lisp? 
> 
> [3]
> 
> The grafic output of the sphere (%i6) looks elliptic.
> As a work around I shorten the gnuplot window by hand, so that (%i6) looks spherical :)
> Is there a possibility to set the aspect ratio, so that 'a sphere looks like a sphere'?
> Or is there an plot option like maple's 'scaling=constrained'?

I'll see what I can do about this.

Bis bald.

-- 
Mario Rodriguez Riotorto
www.biomates.net