#15799: floating point tolerance in gsl fft doctest
-------------------------------------+-------------------------------------
Reporter: vbraun | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.2
Component: numerical | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/vbraun/floating_point_tolerance_in_gsl_fft_doctest|
56d129822e7c549b5f00758fc4707c25e780f64c
Dependencies: | Stopgaps:
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Changes (by vbraun):
* status: new => needs_review
* cc: lftabera, ppurka, mmezzarobba, mhansen (added)
* component: PLEASE CHANGE => numerical
* commit: => 56d129822e7c549b5f00758fc4707c25e780f64c
* type: PLEASE CHANGE => defect
Old description:
New description:
The difference between 4.0=3.9999... and 3.99 is 1e-2, so if you doctest
that with # abs tol 1e-2 then you are numerically unstable.
{{{
sage -t --long src/sage/gsl/fft.pyx
**********************************************************************
File "src/sage/gsl/fft.pyx", line 61, in sage.gsl.fft.FastFourierTransform
Failed example:
a #abs tol 1e-2
Expected:
[(36.0, 0.0), (-4.00, 9.65), (-4.0, 4.0), (-3.99, 1.65), (-4.0, 0.0),
(-4.0, -1.65), (-4.0, -4.0), (-3.99, -9.65)]
Got:
[(36.0, 0.0), (-4.0, 9.65685424949238), (-4.000000000000001,
3.9999999999999996), (-4.000000000000001, 1.6568542494923795), (-4.0,
0.0), (-3.9999999999999996, -1.6568542494923801), (-3.9999999999999996,
-3.9999999999999996), (-3.9999999999999982, -9.65685424949238)]
Tolerance exceeded in 1 of 16
-3.99 vs -4.000000000000001
}}}
--
Comment:
New commits:
||[http://git.sagemath.org/sage.git/commit/?id=56d129822e7c549b5f00758fc4707c25e780f64c
56d1298]||{{{do not abbreviate 3.99999... to 3.99 with # abs tol 1e-2}}}||
--
Ticket URL: <http://trac.sagemath.org/ticket/15799#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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