plot_options defaults and plot2d benchmarking (was: Maxima 5.15.0 release candidate 1)

Hi,
the new version of plot.lisp in the 5.15.0 RC1 has a few new options.
One of them, axes, will specify whether the x, y or both axes should be
displayed. I gave that option the default value true, which means that
the two axes will be shown; I did so because I've heard many users
complain about the lack of axes. But if there are strong feelings about
that, we could keep it false which is the current behavior in 5.14.

I also take this opportunity to show you a comparison of the performance
of 5.15.0 RC1 with 3 different Lisp flavors, under Ubuntu Gutsy, in a
64-bit Intel Quad Core processor. The test was the plotting of a few
implicit functions in 2D (see attached file). As you can see, Clisp is
much slower that Sbcl and GCL in that context:

LISP FLAVOR             RESULT
sbcl             23.0490 seconds (23.2170 elapsed) using 1957.658 MB
gcl              32.5000 seconds (33.1100 elapsed)
clisp           435.7032 seconds (436.4190 elapsed) using 13018.701 MB

In all cases the CPU remained at about 25%, which must be because only
one of the 4 processors is used.

Regards,
Jaime Villate

-------------- next part --------------
F: -x^4/2+4*x^3-3*x^2/2-32*x+25;
U: -integrate(F,x);
p: realroots(F)$
load(implicit_plot)$
ip_grid:[100,100]$
ip_grid_in:[15,15]$
showtime: true$
implicit_plot(makelist(U+3*v^2/20=E,E,[-120,0,20,60,200,rhs(p[1]),rhs(p[3])]),
      [x,-5,8],[v,-40,40],[gnuplot_preamble,"unset key"]);