Opened 14 years ago

Closed 14 years ago

#442 closed defect (duplicate)

RDF roots() function gives imprecise results

Reported by: rlm Owned by: rlm
Priority: major Milestone: sage-2.8.2
Component: basic arithmetic Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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Description

For example:

sage: x = polygen(RDF) sage: f = (x-1)3 sage: f.roots()

[1.00000859959,

0.999995700205 + 7.44736245561e-06*I, 0.999995700205 - 7.44736245561e-06*I]

Change History (3)

comment:1 Changed 14 years ago by rlm

in sage-2.8.1/local/lib/python2.5/site-packages/numpy/lib/polynomial.py, line 116 appears to be casting whatever float type is given to just float.

comment:2 Changed 14 years ago by rlm

This is just as much an issue for eigen_left and eigen_right: sage: g = Matrix(RDF, 0, -9],[1,6?); g [ 0.0 -9.0] [ 1.0 6.0] sage: g.eigen_left() ([3.00000003183, 2.99999996817], .....

comment:3 Changed 14 years ago by rlm

  • Resolution set to duplicate
  • Status changed from new to closed

See ticket #211.

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