#19797: Build GSL in IEEE 754 compliant mode
-------------------------------------+-------------------------------------
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: N/A | Commit:
Branch: | 694feb2d71ebf521cf5f32dba69e0406d16e9f11
u/jdemeyer/ticket/19797 | Stopgaps:
Dependencies: #19796 |
-------------------------------------+-------------------------------------
Changes (by vbraun):
* cc: rws (added)
* commit: => 694feb2d71ebf521cf5f32dba69e0406d16e9f11
Comment:
Isn't this sacrificing a lot of numerical performance? At least IEEE
754-2008 contains fused multiply-add.
The doctest is
{{{
sage: x = var('x', domain='real')
sage: s = abs((1+I*x)^4); s
(I*x + 1)^2*(-I*x + 1)^2
sage: s._plot_fast_callable(x)
<sage.ext.interpreters.wrapper_py.Wrapper_py object at ...>
sage: s._plot_fast_callable(x)(10)
10201
sage: abs((I*10+1)^4)
10201
sage: plot(s)
Graphics object consisting of 1 graphics primitive
}}}
Isn't the real problem that abs does not default to `hold=True`, so
something that ought to be manifestly real is not. Compare:
{{{
sage: abs((1+I*x)^4)._plot_fast_callable(x)(RDF(10))
10201.00000000001
sage: type(_)
<type 'sage.rings.complex_double.ComplexDoubleElement'>
}}}
vs.
{{{
sage: ((1+I*x)^4).abs(hold=True)._plot_fast_callable(x)(RDF(10))
10201.000000000005
sage: type(_)
<type 'sage.rings.real_double.RealDoubleElement'>
}}}
----
New commits:
||[http://git.sagemath.org/sage.git/commit/?id=e4686731d4d1acb1f75b223a0e855bff1c3b8561
e468673]||{{{Simplify build of interpreters by skipping header files}}}||
||[http://git.sagemath.org/sage.git/commit/?id=694feb2d71ebf521cf5f32dba69e0406d16e9f11
694feb2]||{{{Build GSL in IEEE 754 compliant mode}}}||
--
Ticket URL: <http://trac.sagemath.org/ticket/19797#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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