#17157: Improve formula for Bell numbers
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Reporter: jdemeyer | Owner:
Type: enhancement | Status: needs_review
Priority: minor | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jeroen Demeyer | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jdemeyer/ticket/17157 | 0266cef42895b095b8c7eca5718a1466300e1304
Dependencies: | Stopgaps:
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Changes (by jdemeyer):
* commit: => 0266cef42895b095b8c7eca5718a1466300e1304
Old description:
> Improve the error analysis for the implementation of Dobinski's formula
> to compute the Bell numbers leading to
>
> 1. code which is actually consistent with the mathematical formulas
> 1. code which is cleaner and simpler than before, hopefully slightly
> faster
> 1. a complete error estimate including the final real approximation
New description:
Improve the error analysis for the implementation of Dobinski's formula to
compute the Bell numbers leading to
1. code which is actually consistent with the mathematical formulas
1. code which is cleaner and simpler than before
1. a complete error estimate including the final real approximation
1. faster code:
Before:
{{{
sage: timeit('bell_number(200)', number=2000)
2000 loops, best of 3: 1.45 ms per loop
}}}
After:
{{{
sage: timeit('bell_number(200)', number=2000)
2000 loops, best of 3: 441 µs per loop
}}}
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Comment:
New commits:
||[http://git.sagemath.org/sage.git/commit/?id=0266cef42895b095b8c7eca5718a1466300e1304
0266cef]||{{{Improve formula for Bell numbers}}}||
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Ticket URL: <http://trac.sagemath.org/ticket/17157#comment:5>
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