On Saturday 14 March 2009 02:45:13 pm William Stein wrote:
> > William, shall we treat the case where the only variables in the
> > expression is x and y specially, and allow not specifying the variables
> > for the axis then? I think this makes the notation confusing and
> > inconsistent.
>
> I have never ever even once heard of somebody complaining or being
> serious confused because these pop up a plot:
>
> sage:
> sage: plot(sin(u), (-3,3))
> sage: plot3d(x^2 + y^2, (0,3), (-2,3))
>
> I have frequently seen and heard of people being confused by
>
> sage: x(5)
> 5
Evidently, you didn't listen to me approximately 1.5 years ago then. I've
been ardently opposed to the fast-and-loose handling of variables in plot &
friends ever since I started using them. Most of my concrete complaints have
been fixed by the addition of syntax like
sage: parametric_plot((1,t),(t,-12,12))
where the key point is the allowance of 't' in the range tuple.
However, if you are going to make a special case for 'x' and 'y', then, I
don't know what you'd do with this
sage: plot(1,(y,-5,5))
which currently produces a horizontal line from -5 to 5. I don't know what it
should do.
The following a truly sick collection of results (sage 3.3):
sage: var('t,x,y')
(t, x, y)
sage: parametric_plot((1,x),(t,-12,12)) # a vertical line
sage: parametric_plot((1,x),(y,-12,12)) # a vertical line
Yes, those last examples are pathological and stupid, but they should give me
an error so at least I know I'm stupid.
--
Joel
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