#12589: series yields wrong result
-------------------------+--------------------------------------------------
Reporter: dkrenn | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: symbolics | Keywords: series, order, symbolics
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Description changed by dkrenn:
Old description:
> The following was posted by Clemens Heuberger on
> [https://spreadsheets.google.com/pub?key=pCwvGVwSMxTzT6E2xNdo5fA the
> public bug reports from the notebook interface] and on
> [http://groups.google.com/group/sage-
> support/browse_thread/thread/2949e7c3d0e84ef/852fabf0229526ed sage-
> support]. In the latter other code examples were posted.
>
> {{{f.series(q,2)}}} for the {{{f}}} defined below yields {{{Order(q^2)}}}
> which is incorrect, as {{{f.subs(q=0)}}} equals {{{1}}} (which is
> correct).
>
> {{{
> sage: var('q')
> sage: f=(q^13362120470/((q - 1)*(q^5 - 1)*(q^21 - 1)*(q^85 - 1)*(q^341 -
> 1)*(q^1365 - 1)*(q^5461 - 1)*(q^21845 - 1)*(q^87381 - 1)*(q^349525 -
> 1)*(q^1398101 - 1)*(q^5592405 - 1)*(q^22369621 - 1)*(q^89478485 -
> 1)*(q^357913941 - 1)*(q^1431655765 - 1)*(q^5726623061 - 1)) +
> 1)/(q^7635497409/((q - 1)*(q^5 - 1)*(q^21 - 1)*(q^85 - 1)*(q^341 -
> 1)*(q^1365 - 1)*(q^5461 - 1)*(q^21845 - 1)*(q^87381 - 1)*(q^349525 -
> 1)*(q^1398101 - 1)*(q^5592405 - 1)*(q^22369621 - 1)*(q^89478485 -
> 1)*(q^357913941 - 1)*(q^1431655765 - 1)*(q^5726623061 - 1)) + 1)
> sage: f.series(q,2)
> Order(q^2)
> sage: f.subs(q=0)
> 1
> }}}
New description:
The following was posted on
[https://spreadsheets.google.com/pub?key=pCwvGVwSMxTzT6E2xNdo5fA the
public bug reports from the notebook interface] by Clemens Heuberger on
1/4/2011 and on [http://groups.google.com/group/sage-
support/browse_thread/thread/2949e7c3d0e84ef/852fabf0229526ed sage-
support]. In the latter other code examples were posted.
{{{f.series(q,2)}}} for the {{{f}}} defined below yields {{{Order(q^2)}}}
which is incorrect, as {{{f.subs(q=0)}}} equals {{{1}}} (which is
correct).
{{{
sage: var('q')
sage: f=(q^13362120470/((q - 1)*(q^5 - 1)*(q^21 - 1)*(q^85 - 1)*(q^341 -
1)*(q^1365 - 1)*(q^5461 - 1)*(q^21845 - 1)*(q^87381 - 1)*(q^349525 -
1)*(q^1398101 - 1)*(q^5592405 - 1)*(q^22369621 - 1)*(q^89478485 -
1)*(q^357913941 - 1)*(q^1431655765 - 1)*(q^5726623061 - 1)) +
1)/(q^7635497409/((q - 1)*(q^5 - 1)*(q^21 - 1)*(q^85 - 1)*(q^341 -
1)*(q^1365 - 1)*(q^5461 - 1)*(q^21845 - 1)*(q^87381 - 1)*(q^349525 -
1)*(q^1398101 - 1)*(q^5592405 - 1)*(q^22369621 - 1)*(q^89478485 -
1)*(q^357913941 - 1)*(q^1431655765 - 1)*(q^5726623061 - 1)) + 1)
sage: f.series(q,2)
Order(q^2)
sage: f.subs(q=0)
1
}}}
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12589#comment:1>
Sage <http://www.sagemath.org>
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and MATLAB
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