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sympy - issue #4090

Poly.real_roots may return non-real roots

Posted on Oct 31, 2013 by Quick Monkey

Using Python 2.7.5 and sympy 0.7.3:

>>> from sympy import Poly, Symbol >>> p = Symbol('p', nonnegative=True) >>> n = 14 >>> alpha = 0.01 >>> Poly(p**n - alpha).real_roots() [10**(6/7)cos(pi/7)/10 + 10*(6/7)*I*sin(pi/7)/10, 10**(6/7)/10]

A complex root appears also for n in (18, 22, 26, 30).

Comment #1

Posted on Oct 31, 2013 by Happy Elephant

(No comment was entered for this change.)

Comment #2

Posted on Mar 5, 2014 by Happy Elephant

We have moved issues to GitHub https://github.com/sympy/sympy/issues.

Comment #3

Posted on Apr 6, 2014 by Happy Rabbit

Migrated to http://github.com/sympy/sympy/issues/7189

Status: Valid

Labels:
Type-Defect Priority-Medium Polynomial Solvers WrongResult Restrict-AddIssueComment-Commit