Opened 10 years ago
Closed 10 years ago
#8540 closed defect (fixed)
very simple basic sqrt simplification totally broken
Reported by: | was | Owned by: | burcin |
---|---|---|---|
Priority: | blocker | Milestone: | sage-4.3.4 |
Component: | basic arithmetic | Keywords: | |
Cc: | robertwb, mhansen | Merged in: | sage-4.3.4.rc0 |
Authors: | Burcin Erocal | Reviewers: | Mike Hansen |
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
sage: a = 3/4 sage: b = a^(-1/2) sage: b^2 12
But it should be 4/3.
Reported by Paul Nelson, a grad student at Caltech.
Attachments (1)
Change History (7)
comment:1 Changed 10 years ago by
comment:2 Changed 10 years ago by
Even earlier than the square:
sage: (3/4)^(-1/2) 6*sqrt(1/3) sage: n((.75)^(-1/2)) 1.15470053837925 sage: n(6*sqrt(1/3)) 3.46410161513775
comment:3 Changed 10 years ago by
- Cc robertwb mhansen added
During the push for the switch, some code was added to simplify these cases (where the base and exponent are rational, but the result is not exact) further than what ginac can do. See sage.rings.rational.rational_power_parts
for example.
I am taking a look at this right now, but I don't have much time, so I can't promise any results.
Changed 10 years ago by
comment:4 Changed 10 years ago by
- Component changed from symbolics to basic arithmetic
- Status changed from new to needs_review
- Summary changed from ** BLOCKER ** very simple basic sqrt simplification totally broken bad to very simple basic sqrt simplification totally broken
attachment:trac_8540-rational_power.patch fixes the problem, please review.
comment:5 Changed 10 years ago by
- Reviewers set to Mike Hansen
- Status changed from needs_review to positive_review
Looks good.
comment:6 Changed 10 years ago by
- Merged in set to sage-4.3.4.rc0
- Resolution set to fixed
- Status changed from positive_review to closed
Note: See
TracTickets for help on using
tickets.
This serious bug is present in sage-4.0, but not in 3.4.2, so it was caused in the switch to Pynac.