#10042: Doctest failure in sage/rings/polynomial/polynomial_element.pyx
------------------------------+---------------------------------------------
Reporter: mpatel | Owner: mvngu
Type: defect | Status: positive_review
Priority: blocker | Milestone: sage-4.6
Component: doctest | Keywords:
Author: Dima Pasechnik | Upstream: N/A
Reviewer: Leif Leonhardy | Merged:
Work_issues: |
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Comment(by zimmerma):
the gcc documentation says that with {{{-mfpmath=387}}, temporary results
are computed with 80
bits of precision (i.e., with double extended precision), thus different
results might be
obtained. It also points to {{{-ffloat-store}}}, which prevents using
extended precision.
With {{{-ffloat-store}}} I get on a 64-bit Core 2 (and without it, I get
different absolute
values for float, exactly as Dave in the above comment):
{{{
tarte% gcc -ffloat-store -mfpmath=387 test3.c -lm
tarte% ./a.out
float:
+1.7724539041519165039062500000000000000000000000000000000000000000000000
-1.7724539041519165039062500000000000000000000000000000000000000000000000
double:
+1.7724538509055158819194275565678253769874572753906250000000000000000000
-1.7724538509055158819194275565678253769874572753906250000000000000000000
long double:
+1.7724538509055159927248895845863785325491335242986679077148437500000000
-1.7724538509055159927248895845863785325491335242986679077148437500000000
}}}
I thus suggest to recompile Lapack with {{{-ffloat-store}}} and try again.
Paul
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10042#comment:79>
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