#18393: make Expression.series return an element of SR[[]]
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Reporter: rws | Owner:
Type: | Status: positive_review
enhancement | Milestone: sage-duplicate/invalid/wontfix
Priority: major | Resolution:
Component: calculus | Merged in:
Keywords: | Reviewers:
Authors: | Work issues:
Report Upstream: N/A | Commit:
Branch: | Stopgaps:
Dependencies: |
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Comment (by mmezzarobba):
Replying to [comment:14 nbruin]:
> The problem is: there are SR allows expressions of such generality that
series expansions aren't always possible. Consider:
> {{{
> sage: function('f')
> sage: s=series(sin(x))
> sage: f(cos(x))+g
> }}}
(I guess `g` should be `s`?)
> Should that be considered a series in x?
Here Maple does (when one explicitly asks for a series expansion, of
course):
{{{
#-->series(f(cos(x)) + sin(x), x);
series(f(1)+1*x+(-1/2*D(f)(1))*x^2-1/6*x^3+(1/24*D(f)(1)+1/8*`@@`(D,2)(f)(1))*x^4+1/120*x^5+O(x^6),x,6)
}}}
and I found that convenient on many occasions. But I seem to rememer that
ginac can do something similar.
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Ticket URL: <http://trac.sagemath.org/ticket/18393#comment:15>
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