#19797: Build GSL in IEEE 754 compliant mode
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Reporter: jdemeyer | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-7.0
Component: packages: | Resolution:
standard | Merged in:
Keywords: | Reviewers:
Authors: Jeroen Demeyer | Work issues:
Report Upstream: Reported | Commit:
upstream. Developers acknowledge | 694feb2d71ebf521cf5f32dba69e0406d16e9f11
bug. | Stopgaps:
Branch: |
u/jdemeyer/ticket/19797 |
Dependencies: #19796 |
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Comment (by vbraun):
Its not just that there is no guarantee against numerical noise in the
imaginary part of `exp(I*x)+exp(-I*x)`, the return type of the fast
callable also changes from real to complex (comment:2). The symbolic
expression containing abs() should only do automatic simplifications that
are again manifestly real.
* Expanding polynomials over QQ[I] is safe, and that is the only safe case
I can think of
* Transcendental functions are not safe
* Expanding polynomials whose coefficients are radical expressions over
QQ[I] are not safe
Thoughts?
--
Ticket URL: <http://trac.sagemath.org/ticket/19797#comment:16>
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