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[Bug-gsl] Bug in polynomial root finder
From: |
Munagala Ramanath |
Subject: |
[Bug-gsl] Bug in polynomial root finder |
Date: |
Sat, 29 Oct 2011 08:22:53 -0700 (PDT) |
Hi,
I'm using GSL via Ruby and just found a polynomial for which it fails to find
roots. However,
I can plug this polynomial into some of the root finders on the web and they
find roots with
no problems. Here is the code (coefficient array is in reverse order):
----------------------------------------------
#!/usr/bin/ruby
require 'gsl'
# shows bug in GSL polynomial root finder
p = [1, -4, 2, 10, -17, 10, 6, -16, 12, -16, 16, -8, 28, -8, -48, 32]
roots = GSL::Poly[ p.reverse ].solve
puts roots
----------------------------------------------
The output when I run it is:
ruby gsl_bug.rb
gsl_bug.rb:7:in `complex_solve': Ruby/GSL error code 5, root solving qr method
failed to converge (file zsolve.c, line 78), generic failure
(GSL::ERROR::EFAILED)
from gsl_bug.rb:7:in `<main>'
Thanks for any help.
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