Opened 7 years ago
Last modified 6 years ago
#14897 new enhancement
binomial(x, m) gives incorrect answer when m is float
Reported by: | ppurka | Owned by: | AlexGhitza |
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Priority: | major | Milestone: | sage-6.4 |
Component: | basic arithmetic | Keywords: | binomial |
Cc: | Merged in: | ||
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
Essentially, this stuff
sage: binomial(10, 0.1) 1
What I would have expected it to give as output is
sage: gamma(10+1)/gamma(10-0.1+1)/gamma(0.1+1) 1.32919082253922
This enhancement has to be done on the sage side since both mpir and pari don't give the correct answer. Using the gamma function in these special cases will also take care of complex numbers.
But, we must avoid changing the whole implementation to the gamma function - that was also giving incorrect results and was fixed in #12448. The sage.rings.arith.binomial
function itself is a bit of a mess and it is hard to figure out what will eventually get executed in that code.
Change History (3)
comment:1 Changed 7 years ago by
- Milestone changed from sage-6.1 to sage-6.2
comment:2 Changed 7 years ago by
- Milestone changed from sage-6.2 to sage-6.3
comment:3 Changed 6 years ago by
- Milestone changed from sage-6.3 to sage-6.4
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