Opened 9 years ago

Closed 9 years ago

#14115 closed defect (fixed)

missing log attribute for power series

Reported by: chapoton Owned by: AlexGhitza
Priority: minor Milestone: sage-5.8
Component: algebra Keywords: logarithm, power series, days45
Cc: Merged in: sage-5.8.beta0
Authors: Frédéric Chapoton Reviewers: Travis Scrimshaw
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Status badges

Description (last modified by chapoton)

Consider the following 

sage: x=PowerSeriesRing(QQ,'x').gen()
sage: x.exp()                        
1 + x + 1/2*x^2 + 1/6*x^3 + 1/24*x^4 + 1/120*x^5 + 1/720*x^6 + 1/5040*x^7 + 1/40320*x^8 + 1/362880*x^9 + 1/3628800*x^10 + 1/39916800*x^11 + 1/479001600*x^12 + 1/6227020800*x^13 + 1/87178291200*x^14 + 1/1307674368000*x^15 + 1/20922789888000*x^16 + 1/355687428096000*x^17 + 1/6402373705728000*x^18 + 1/121645100408832000*x^19 + O(x^20)
sage: x.log()
AttributeError                            Traceback (most recent call last)
...
AttributeError: 'sage.rings.power_series_poly.PowerSeries_poly' object has no attribute 'log'

I think it would be good to have log if one has exp, in order to be able to go back and forth. Of course, one should check that the constant term is 1.

Here is a patch that does the job.

Attachments (2)

trac_14115-fc.patch​ (5.9 KB) - added by chapoton 9 years ago.
trac_14155-review-ts.patch​ (1.1 KB) - added by tscrim 9 years ago.

Download all attachments as: .zip

Change History (7)

Changed 9 years ago by chapoton

comment:1 Changed 9 years ago by chapoton

  • Description modified (diff)
  • Status changed from new to needs_review

comment:2 Changed 9 years ago by chapoton

  • Authors set to Frédéric Chapoton

Changed 9 years ago by tscrim

comment:3 Changed 9 years ago by tscrim

  • Keywords days45 added
  • Reviewers set to Travis Scrimshaw

Hey Frederic,

Looks good. I've uploaded a small review patch which tweaks the documentation. If you agree with my changes, go ahead and set this to positive review.

Best,
Travis

comment:4 Changed 9 years ago by chapoton

  • Status changed from needs_review to positive_review

ok, then positive review

comment:5 Changed 9 years ago by jdemeyer

  • Merged in set to sage-5.8.beta0
  • Resolution set to fixed
  • Status changed from positive_review to closed
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