Opened 6 years ago
Closed 8 months ago
#15334 closed defect (fixed)
Evaluation of Jacobi elliptic functions for non-real arguments depends on previously computed values
Reported by: | davidamadore | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-8.9 |
Component: | numerical | Keywords: | special function elliptic integral jacobi |
Cc: | jakobkroeker, vklein | Merged in: | |
Authors: | Frédéric Chapoton | Reviewers: | Vincent Klein |
Report Upstream: | N/A | Work issues: | |
Branch: | 4dd9669 (Commits) | Commit: | 4dd9669aff58380d98e88b6ba06ced9ece823684 |
Dependencies: | Stopgaps: |
Description
The following example shows that numerically evaluating sn(I,1/2) first fails ("cannot evaluate symbolic expression numerically") and then succeeds once the value sc(1,1/2) has been computed:
sage: N(jacobi("sn", I, 1/2)) --------------------------------------------------------------------------- TypeError Traceback (most recent call last) <ipython-input-1-e0000742d9d6> in <module>() ----> 1 N(jacobi("sn", I, Integer(1)/Integer(2))) /usr/src/local/sage-5.12/local/lib/python2.7/site-packages/sage/misc/functional.pyc in numerical_approx(x, prec, digits) 1395 prec = int((digits+1) * LOG_TEN_TWO_PLUS_EPSILON) + 1 1396 try: -> 1397 return x._numerical_approx(prec) 1398 except AttributeError: 1399 from sage.rings.complex_double import is_ComplexDoubleElement /usr/src/local/sage-5.12/local/lib/python2.7/site-packages/sage/symbolic/expression.so in sage.symbolic.expression.Expression._numerical_approx (sage/symbolic/expression.cpp:22615)() TypeError: cannot evaluate symbolic expression numerically sage: N(jacobi("sc", 1, 1/2)) 1.34737147138542 sage: N(jacobi("sn", I, 1/2)) 1.34737147138542*I
(in fact, evaluating sc with any arguments whatsoever seems to make the sn function work afterward).
Change History (10)
comment:1 Changed 6 years ago by
- Milestone changed from sage-6.1 to sage-6.2
comment:2 Changed 6 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
comment:4 Changed 3 years ago by
- Cc jakobkroeker added
comment:5 Changed 8 months ago by
- Branch set to u/chapoton/15334
- Commit set to 4dd9669aff58380d98e88b6ba06ced9ece823684
- Milestone changed from sage-6.4 to sage-8.9
- Status changed from new to needs_review
comment:7 Changed 8 months ago by
comment:8 Changed 8 months ago by
- Reviewers set to Vincent Klein
- Status changed from needs_review to positive_review
Looks good to me.
comment:10 Changed 8 months ago by
- Branch changed from u/chapoton/15334 to 4dd9669aff58380d98e88b6ba06ced9ece823684
- Resolution set to fixed
- Status changed from positive_review to closed
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seems fixed meanwhile, needs a test?