#10042: Doctest failure in sage/rings/polynomial/polynomial_element.pyx
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Reporter: mpatel | Owner: mvngu
Type: defect | Status: needs_work
Priority: blocker | Milestone: sage-4.6
Component: doctest | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: report upstream |
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Comment(by zimmerma):
> Since Paul pointed out that there is some linear algorithm going on here
from deep within numpy, it seems unlikely that this is what is going on.
yes it seems the computation is done by the lapack {{{dgeev}}} routine.
From the source file
{{{dgeev.f}}} in the Sage distribution, it does not call {{{POW}}} however
it calls {{{SQRT}}}. But the square root is a
standard IEEE function. What could happen however is that on some machines
lapack could use
double extended precision (i.e., 64-bit instead of 53-bit significand).
One way to debug this is to add print statements in the {{{dgeev.f}}}
file, recompile lapack and see the difference between two different
computers. How can one (easily) recompile and build a
spkg (I guess {{{sage -br}}} will not do that)?
Paul
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10042#comment:44>
Sage <http://www.sagemath.org>
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