#12181: random_DAG does not terminate on it's default inputs
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Reporter: mderickx | Owner: tbd
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.3
Component: graph theory | Resolution:
Keywords: random digraph | Work issues:
Report Upstream: N/A | Reviewers: David Coudert
Authors: dsm, Frédéric Chapoton | Merged in:
Dependencies: | Stopgaps:
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Comment (by chapoton):
> - The instruction {{{weight_max=ZZ(weight_max)}}} is before the test on
weights. Is this what you expect?
> {{{
> sage: random_DAG(5,.5,1.5)
>
---------------------------------------------------------------------------
> TypeError Traceback (most recent call
last)
> ...
> TypeError: Attempt to coerce non-integral RealNumber to Integer
> }}}
Yes, indeed. Well, this seems to be a reasonable way to ensure that the
input is of correct type, as specified in the documentation. The problem
is that one should accept both '''int''' and '''Integers''' as third
argument. This is the case with what I have written, which tries to coerce
to Integers.
> - The output is not only a dictionary but a dictionary of dictionary.
You should perhaps add a warning comment since the space requirement for
large values of n could be too high. I don't know the usual size of the
DAG used in this context.
Well, a dictionary of dictionaries is a dictionary, isn't it ? And by the
way, I have not found any place in the sources of Sage where this
procedure is used.
> - I'm unable to build/find the documentation. Are you able to build it?
Sorry, I do not understand this remark. I have only tried the doc in a
terminal. Should I try it in the notebook too ? Should I do something else
? Could you pinpoint a specific problem ?
> - I agree that moving this function into digraphs_generator could be
done as part of another patch. It should in particular have an optional
argument allowing to have multiple sinks (and so avoiding the while loop).
With current setting, I'm not sure that the average number of arcs is
``p*n``.
Well, this ticket is here to solve a specific problem, and the rest can be
postponed to some other ticket.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12181#comment:18>
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