(Newbie) Problem plotting numerical integrations



On Tue, 2008-09-02 at 19:19 -0400, Richard Hennessy wrote:
> Try
> plot3d('(r(x,y)),[x,-1,1],[y,-1,1],[grid,50,50],[gnuplot_pm3d,true]);
> that worked for me.

Strange; no luck here (although the error changes)... 

-----
Maxima 5.13.0 http://maxima.sourceforge.net
Using Lisp GNU Common Lisp (GCL) GCL 2.6.8 (aka GCL)
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
This is a development version of Maxima. The function bug_report()
provides bug reporting information.
(%i1) V(p):=max(0,1-sqrt(p.p));
(%o1)                   V(p) := max(0, 1 - sqrt(p . p))
(%i2) r(x,y):=quad_qags(V([x,y,z]),z,-1,1)[1];
(%o2)           r(x, y) := quad_qags(V([x, y, z]), z, - 1, 1)
                                                             1
(%i3)
plot3d('(r(x,y)),[x,-1,1],[y,-1,1],[grid,50,50],[gnuplot_pm3d,true]);

Maxima encountered a Lisp error:

 Error in PROGN [or a callee]: Expected a LONG-FLOAT 

Automatically continuing.
To reenable the Lisp debugger set *debugger-hook* to nil.
-----
(Same thing happens with romberg too).

What version of maxima/lisp are you using ?

Tim