#8054: roots(algorithm='numpy') does not work in arbitrary precision
-------------------------+--------------------------------------------------
Reporter: zimmerma | Owner: jkantor
Type: defect | Status: new
Priority: major | Milestone: sage-4.3.2
Component: numerical | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-------------------------+--------------------------------------------------
Consider the following example:
{{{
sage: R.<x> = PolynomialRing(ComplexField(3322))
sage: p=x^4+54*x^2+154
sage: z=p.roots(algorithm='pari')
sage: e=p-mul([x-z[i][0] for i in range(4)])
sage: n(max(abs(e.coeffs()[i]) for i in range(0,e.degree()+1)))
6.08883742371831e-999
}}}
This is ok. Compare now with:
{{{
sage: R.<x> = PolynomialRing(ComplexField(3322))
sage: p=x^4+54*x^2+154
sage: z=p.roots(algorithm='numpy')
sage: e=p-mul([x-z[i][0] for i in range(4)])
sage: n(max(abs(e.coeffs()[i]) for i in range(0,e.degree()+1)))
6.06533797844328e-14
}}}
Clearly the precision given by numpy is only 14 digits, not 1000
digits as expected.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8054>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
