#7822: pynac log function cannot handle float arguments <= 0
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Reporter: burcin | Owner: burcin
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.3.1
Component: symbolics | Keywords:
Work_issues: | Author: Burcin Erocal
Upstream: N/A | Reviewer:
Merged: |
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Changes (by burcin):
* status: needs_work => needs_review
Comment:
attachment:trac_7822-py_log.take2.patch fixes the speed problems, although
it is still not as fast as before. It depends on a very small patch to
pynac. I will post a pynac package with the fix later this week.
Before:
{{{
sage: %timeit t = ln(float(-1))
1000 loops, best of 3: 285 µs per loop
sage: %timeit t = ln(float(1))
100000 loops, best of 3: 17.5 µs per loop
sage: %timeit t = ln(complex(1))
100000 loops, best of 3: 6.25 µs per loop
sage: %timeit t = ln(complex(1,1))
100000 loops, best of 3: 6.4 µs per loop
sage: %timeit t = ln(complex(1,-1))
100000 loops, best of 3: 6.42 µs per loop
sage: %timeit t = ln(complex(0))
100000 loops, best of 3: 9.24 µs per loop
sage: %timeit t = ln(complex(-1))
100000 loops, best of 3: 6.21 µs per loop
}}}
After:
{{{
sage: %timeit t = ln(float(-1))
100000 loops, best of 3: 15.2 µs per loop
sage: %timeit t = ln(float(1))
100000 loops, best of 3: 13.2 µs per loop
sage: %timeit t = ln(complex(1))
100000 loops, best of 3: 15 µs per loop
sage: %timeit t = ln(complex(1,1))
100000 loops, best of 3: 15.3 µs per loop
sage: %timeit t = ln(complex(0))
100000 loops, best of 3: 15.5 µs per loop
sage: %timeit t = ln(complex(-1))
100000 loops, best of 3: 15.1 µs per loop
}}}
Re comment:3:
The top level log function is a regular python function which handles
precision, etc. Calling that in the doctest is not really testing the
`Function_log` defined in `sage/functions/log.py`. If we want people to
move away from using `ln`, we should deprecate it. Since the last
discussion about this topic ended up by concluding we should even support
printing `ln` instead of `log`, I don't see that happening soon.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7822#comment:4>
Sage <http://www.sagemath.org>
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