[Numpy-discussion] Numeric eigenvectors problem on Linux

Alexandre Gillet gillet at scripps.edu
Thu Feb 5 14:46:06 CST 2004


Thanks Konrad,

The test runs on our others machines return similar result.
Also Nils explanation  give us a better understanding of what was going on.

Thanks again
Alex

Konrad Hinsen wrote:
> On Tuesday 03 February 2004 23:43, Alexandre Gillet wrote:
> 
> 
>>The same calculation return the correct value on Windows,SUN,SGI.
>>All the Numeric were built without out modifying the setup.py file. I
>>just run python setup.py install  (python2.3, Numeric 23.0)
>>
>>The test script we run is the following:
>>import Numeric
>>import LinearAlgebra
>>e = Numeric.array([[ 0.6875,-0.3125,0.3125],
>>                    [-0.3125 , 0.6875 , 0.3125],
>>                    [ 0.3125 , 0.3125 , 0.6875]])
>>evals, evecs = LinearAlgebra.eigenvectors(e)
>>print "----------------------------------"
>>print "evecs",evecs
>>
>>
>>on Linux we  get:
>>evals [ 1.      0.0625  1.    ]
>>evecs [[ 0.81649658 -0.40824829  0.40824829]
>>	 [-0.57735027 -0.57735027  0.57735027]
>>  	[-0.26840956  0.80201256  0.533603  ]]
> 
> 
> I get the same results. Checking with
> 
>   print Numeric.dot(evecs, e)-evals[:, Numeric.NewAxis]*evecs
> 
> yields
> 
> array([[  0.00000000e+00,  -5.55111512e-17,   5.55111512e-17],
>        [ -4.16333634e-17,  -4.16333634e-17,   4.16333634e-17],
>        [  5.55111512e-17,   0.00000000e+00,   0.00000000e+00]])
> 
> which doesn't look so bad. What does the same test produce on your other 
> machines?
> 
> Konrad.

-- 
   o Alexandre Gillet               email: gillet at scripps.edu
  /  The Scripps Research Institute,
o   Dept. Molecular Biology,  MB-5,
  \  10550  North Torrey Pines Road,
   o La Jolla,  CA 92037-1000,  USA.
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