#16137: lazy_list from various input data
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Reporter: MatthieuDien | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-7.0
Component: misc | Resolution:
Keywords: LazyPowerSeries, | Merged in:
lazy_list, days57 | Reviewers: Daniel Krenn
Authors: Matthieu Dien, | Work issues:
Vincent Delecroix, Daniel Krenn | Commit:
Report Upstream: N/A | 72a212c34c0f2a172b9d7ac95d11f24d254a86c3
Branch: u/dkrenn/16137 | Stopgaps:
Dependencies: |
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Comment (by mantepse):
This is wonderful!
Yes, today I started to recollect what I want to do. I'm not sure whether
there is any need for another object "stream". Rather, I think that the
next step is a good lazy power series implementation.
The main complication is that it is useful to define power series
recursively, as in
{{{
sage: sage: L = LazyPowerSeriesRing(QQ)
sage: one = L(1)
sage: monom = L.gen()
sage: s = L()
sage: s._name = 's'
sage: s.define(one+monom*s*s)
sage: [s.coefficient(i) for i in range(6)]
[1, 1, 2, 5, 14, 42]
}}}
In the current code, this is done by keeping track of the "approximate
order" of the power series. Note that there are no initial values
provided by the user.
An earlier attempt was done by Mike Hansen in #15673, so I guess it's best
to continue discussion there. I also have code (for FriCAS, however) that
generalizes this using a different approach, via undetermined coefficients
and given initial values.
I guess that I am a terrible python programmer, but I think I can give it
a try. I would start with what Mike has written, but first I want to
recollect how these recursive definitions worked.
--
Ticket URL: <http://trac.sagemath.org/ticket/16137#comment:99>
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