#18952: heavy performance regression with real/imag(ex)
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Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.8
Component: performance | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by rws):
Profiling with callgrind reveals remarkable things, even with only 6 f's.
Although Pynac accounts for less than 1 per cent of the time, a whopping
150,000 of numerics are created; 88,000 calls to `ex::is_zero`; 50,000 to
`Integer(long)`. The 3,400 calls of `atan2` show that the formula
`power(abs(basis),c)*exp(-d*atan2(b,a))*cos(c*atan2(b,a)+d*log(abs(basis)))`
is used to compute `real((1/3)^(1/2))` over and over.
The simplest solution would be to expand before taking the real part in
Pynac.
However, there is probably more in this use case regarding performance
improvement.
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Ticket URL: <http://trac.sagemath.org/ticket/18952#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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