Opened 14 months ago
Closed 13 months ago
#32016 closed enhancement (fixed)
Fix hurwitz_zeta(0, x) not expanding
Reported by: | pluschny | Owned by: | |
---|---|---|---|
Priority: | minor | Milestone: | sage-9.4 |
Component: | symbolics | Keywords: | hurwitz_zeta |
Cc: | slelievre | Merged in: | |
Authors: | Frédéric Chapoton | Reviewers: | Peter Luschny |
Report Upstream: | N/A | Work issues: | |
Branch: | 785b4e2 (Commits, GitHub, GitLab) | Commit: | 785b4e27162892519d6bb1d5208551893e28a52e |
Dependencies: | Stopgaps: |
Description (last modified by )
Having defined:
def B(n, x): return -n*hurwitz_zeta(1 - n, x) if n != 0 else 1
we expect expand(B(n, x))
to
match bernoulli_polynomial(x, n)
.
Using this small utility function to compare them:
def table(nmax): nab = [('n', 'expand(B(n, x))', 'bernoulli_polynomial(x, n)')] nab.extend([(n, expand(B(n, x)), bernoulli_polynomial(x, n)) for n in range(nmax + 1)]) k = len(str(nmax)) m = max(len(str(x)) for t in nab for x in t) hline = '-' * (k + m + 7) print(hline) for n, a, b in nab: print(f' %{k}s %{m}s' % (n, a)) print(f' %{k}s %{m}s' % ('', b)) print(hline)
we notice they match except for n = 1:
sage: table(4) ---------------------------------- n expand(B(n, x)) bernoulli_polynomial(x, n) ---------------------------------- 0 1 1 ---------------------------------- 1 -hurwitz_zeta(0, x) x - 1/2 ---------------------------------- 2 x^2 - x + 1/6 x^2 - x + 1/6 ---------------------------------- 3 x^3 - 3/2*x^2 + 1/2*x x^3 - 3/2*x^2 + 1/2*x ---------------------------------- 4 x^4 - 2*x^3 + x^2 - 1/30 x^4 - 2*x^3 + x^2 - 1/30 ----------------------------------
This ticket fixes that case.
Change History (7)
comment:1 Changed 14 months ago by
- Branch set to u/chapoton/32016
- Commit set to 785b4e27162892519d6bb1d5208551893e28a52e
- Status changed from new to needs_review
comment:2 Changed 14 months ago by
- Status changed from needs_review to positive_review
Looks good to me. Merci!
comment:3 Changed 14 months ago by
reviewer full name please
comment:4 Changed 14 months ago by
- Reviewers set to Peter Luschny
I don't know if I am qualified as a reviewer in the sense of the SageMath organization.
comment:5 Changed 14 months ago by
- Cc slelievre added
- Description modified (diff)
- Keywords hurwitz_zeta added
- Summary changed from hurwitz_zeta(0, x) does not expand to Fix hurwitz_zeta(0, x) not expanding
- Type changed from PLEASE CHANGE to enhancement
I don't know if I am qualified as a reviewer in the sense of the SageMath organization.
You are!
comment:6 Changed 14 months ago by
- Description modified (diff)
comment:7 Changed 13 months ago by
- Branch changed from u/chapoton/32016 to 785b4e27162892519d6bb1d5208551893e28a52e
- Resolution set to fixed
- Status changed from positive_review to closed
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fixed, please review
New commits:
Hurwitz zeta at n=0