Raymond Toy ?????:
>>>>>>"James" == James Amundson <amundson@users.sourceforge.net> writes:
>
>
> James> I'm worried, however, that this line of thought leads to a routine that
> James> produces potentially misleading results. What does a plot of
> James> sqrt(sin(x^2+y^2)),[x,-4,4],[y,-4,4]
> James> look like using this algorithm?
>
> Good question. But coerce-float-fun takes the realpart, so we get the
> realpart of the sqrt. (Well, the code says that. I didn't try it.)
>
> Ray
>
Realpart seems to be working, but plot2d(asin(x),[x,-2,2]) looks
strange. Left part should be -%PI/2. Why it positive?
In general, what if the function is only piece-wise well defined?
Not sqrt(of something negative) -> 0, but due to some
other reason? Maybe Maxima is just unable to compute numerical
value, like in plot3d(gamma(x+%i*y),[x,-3,3],[y,-1,1]).
And this problem relates both to 2D and 3D plotting.
I've checked Maple and Maxima - it seems that they just
don't plot points where numerical value can't be computed.
BTW, now I understand that my idea to abort plotting after
10 or 20 unsuccessful samples is not so good. These samples
may occasionally fit into not-wel-defined region.
But in any case at least some sanity chek is required.
We should not produce plot is none of the sumples is
good.
--
Vadim V. Zhytnikov
<vvzhy@mail.ru>
<vvzhy@netorn.ru>