#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 (numpy) |
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Comment(by zimmerma):
> Feel free to place any commands here that would enable someone to easily
replicate what you found on another machine, by the way.
Here is what I did on Dave's machine:
{{{
R.<x> = RealField(200)[]
f = x^2 - R(pi)
import numpy
coeffs = f.list()
ty = float
numpy_dtype='double'
numpy_array=numpy.array([ty(c) for c in
reversed(coeffs)],dtype=numpy_dtype)
ext_rts1 = numpy.roots(numpy_array)
ext_rts1[0]
ext_rts1[1]
p=numpy_array
from numpy.lib.shape_base import hstack, atleast_1d
p = atleast_1d(p)
import numpy.core.numeric as NX
non_zero = NX.nonzero(NX.ravel(p))[0]
trailing_zeros = len(p) - non_zero[-1] - 1
p = p[int(non_zero[0]):int(non_zero[-1])+1]
N = len(p)
from numpy.lib.twodim_base import diag, vander
A = diag(NX.ones((N-2,), p.dtype), -1)
A[0, :] = -p[1:] / p[0]
from numpy.linalg import eigvals, lstsq
roots = eigvals(A)
roots[0]
roots[1]
from numpy.core import asarray, inexact, complexfloating, zeros, double
a = copy(A)
a = asarray(a)
wrap = getattr(a, "__array_wrap__", a.__array_wrap__)
t = double
result_t = double
from numpy.linalg import lapack_lite
n = a.shape[0]
dummy = zeros((1,), t)
wr = zeros((n,), t)
wi = zeros((n,), t)
lwork = 1
work = zeros((lwork,), t)
lapack_routine = lapack_lite.dgeev
results = lapack_routine('N', 'N', n, a, n, wr, wi,
dummy, 1, dummy, 1, work, -1, 0)
res=wr.astype(result_t)
res[0]
res[1]
}}}
Paul
PS: it seems the final {{{wr}}} value is not always correctly set,
sometimes I got 0.0 for
res[0] and res[1].
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10042#comment:25>
Sage <http://www.sagemath.org>
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