Raymond Toy ?????:
> Several issues about plotting follow.
>
> In bug 552724 there is an example plot:
>
> plot2d([5-x^2,x+3],[x,-2,1]);
>
> With both openmath, the range of y is limited to -3 to +3 by the plot
> options. I think this is a bug. We shouldn't limit the y range unless
> specifically told to.
>
Now it works fine to me. Thanks for the fix.
>
> If I specify
>
> plot2d([5-x^2],[x,-2,1],[y,-5,5])
>
> this produces the desired openmath plot. However, if I want to use
> gnuplot, the command
>
> plot2d([5-x^2],[x,-2,1],[y,-5,5,plot_format,gnuplot])
>
> produces an error because maxima wants just 2 items after y. I think
> this is a bug. Making plot_format come first fixes this. I think we
> should really specify the y option as y,[-5,5] instead of y,-5,5.
> Then we get a uniform specification of the option name followed by
> exactly one value of either the value or a list of values.
As far as I understand the general form of plot2d
(and similarly plot3d) is
plot2d(expression,range,option1,option2,...);
with option having the form [option_name,value1,value2,...].
So it should be
plot2d([5-x^2],[x,-2,1],[y,-5,5],[plot_format,gnuplot]);
and it actually works. It also works for me with gnuplot.
Maybe make install should take care of mgnuplot and install it somewhere.
>
> Also, if you use gnuplot, no plot is actually produced. I think the
> reason is that what maxima writes out includes lines like
>
> move x y
>
> where x and y are numbers. These aren't valid gnuplot values, so I
> think gnuplot just gives up. I have a hack to not print these lines,
> and a plot is produced, but I'm not sure that is the right thing. I
> don't understand why there are those move lines at all. (A left over
> from PS plotting?)
>
> Finally, it's impossible for the average person to figure out how to
> use plot2d because describe just says:
>
> - Function: PLOT2D (expr,range,...,options,..)
>
> We need a little bit more here. :-) I'll try to cook up some docs for
> this.
>
> I haven't filed any of these a bugs, but if you want me to, I can. I
> was planning on fixing these soon.
>
> Ray
Plaing with plot3d I noticed yes another bug
plot3d(1,[x,0,3],[y,0,3]);
plot3d(sin(x),[x,0,3],[y,0,3]);
produce lisp errors. It seems that plot3d require the expression to
have explicit dependence on exactly two plotting range variables.
Notice that
plot2d(1,[x,0,3]);
works well.
Another bad feature. Type in plot3d option results in
lisp error once again.