Ralf Hemmecke wrote:
>
> On 02/10/2015 01:14 AM, Waldek Hebisch wrote:
> > (3) -> st: Stream K := repeating([1,2,3])
> >>
> >> _____
> >> (3) [1,2,3]
>
> > AFAICS series is fine, the problem is with printing: by default
> > coercion to OutputForm tries to print all known coefficients of
> > the series.
>
> Hmm. Strange. I came to the same conclusion that printing must be the
> problem, but then why didn't I run into the same problem with
>
> st: Stream K := repeating([1])
>
> The stopping criteria here...
>
> https://github.com/fricas/fricas/blob/master/src/algebra/pscat.spad#L291
>
> for n in (count + 1).. while explicitEntries? uu and _
> not eq?(uu, rst uu) repeat
>
> obviously only tests for cycles of length 1.
>
> First of all, doesn't the default
>
> showAll?() == true
>
> look a bit dangerous? In fact, the problem with my example wouldn't have
> been there if showAll?() would be false.
>
> > We probably should change this default, to
> > only show fixed number of coefficients.
>
> The variable _$streamCount$Lisp is 10 in my case. So that would actually
> be fine.
>
> There is also a variable _$streamsShowAll$Lisp. Which is false by
> default (comes from ")set streams showall off"). I would have expected
> that infinite series respect this variable. But that's seemingly not the
> case.
>
> My suggestion would be to have at least
>
> showAll?() ==
> NULL(_$streamsShowAll$Lisp)$Lisp => false
> true
Actually, this is enough:
showAll?() == _$streamsShowAll$Lisp
> But even then the user must be warned when dealing with cyclic streams.
> I've no idea how this should be done, but letting the user blindly run
> into exausted memory isn't the best idea.
In few hours (now have to something else) I will add code to detect
repeating streams. No need to warn: just print 'O(...)' term like
for streams having unevaluated tail.
--
Waldek Hebisch
[email protected]
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