[SciPy-user] problems with scipy.test() on Opteron 64-bit

Giovanni Samaey Giovanni.Samaey at cs.kuleuven.ac.be
Thu Nov 25 07:40:12 CST 2004


Pearu Peterson wrote:

>
>
> On Thu, 25 Nov 2004, Giovanni Samaey wrote:
>
>> What is remarkable is that, the error is the same in the 3 cases.  
>> Moreover, if you add up the first two components of array1 you get 
>> the first component of array2.
>
>
> It would look like atlas bug but since the same results are obtained 
> with Fortran blas/lapack, then I don't know what is happening. I 
> presume that
> you did
>   rm -rf build

Of course. If I would forget, I would notice that nothing would be 
built, anyway...

> What happens when you call geev routine directly? Try for example:
>
> In [1]: import scipy
>
> In [2]: scipy.linalg.flapack.dgeev([[1,2,3],[1,2,3],[2,5,6]],0,0)
> Out[2]:
> (array([  9.32182538e+00,  -6.03426271e-16,  -3.21825380e-01]),
>  array([ 0.,  0.,  0.]),
>  array([       [ 0.,  0.,  0.]]),
>  array([       [ 0.,  0.,  0.]]),
>  0)
>
> In [3]: scipy.linalg.flapack.sgeev([[1,2,3],[1,2,3],[2,5,6]],0,0)
> Out[3]:
> (array([  9.32182503e+00,  -2.82419336e-07,  -3.21825117e-01],'f'),
>  array([ 0.,  0.,  0.],'f'),
>  array([       [ 0.,  0.,  0.]],'f'),
>  array([       [ 0.,  0.,  0.]],'f'),
>  0)
>
> In [4]: scipy.linalg.calc_lwork.geev('d',3)
> Out[4]: (12, 102)
>
> Is there any difference in your case?

Yes there is; in fact there is a difference in all three.

In[1]: import scipy
In[2]: scipy.linalg.flapack.dgeev([[1,2,3],[1,2,3],[2,5,6]],0,0)
Out[2]: (array([ 9.43719064, -0.11536526, -0.32182538]),
array([ 0.,  0.,  0.]),
array([       [ 0.,  0.,  0.]]),
array([       [ 0.,  0.,  0.]]),
0)
In[3]: scipy.linalg.flapack.sgeev([[1,2,3],[1,2,3],[2,5,6]],0,0)
Out[3]: (array([ 0.,  0.,  0.],'f'),
array([ 0.,  0.,  0.],'f'),
array([       [ 0.,  0.,  0.]],'f'),
array([       [ 0.,  0.,  0.]],'f'), 3)
In[4]: scipy.linalg.calc_lwork.geev('d',3)
Out[4]: (12, 174)

Giovanni


>
> Pearu
>
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-- 
Giovanni Samaey		 	http://www.cs.kuleuven.ac.be/~giovanni/ 
Katholieke Universiteit Leuven 	      email: giovanni at cs.kuleuven.ac.be 
Departement Computerwetenschappen                  phone: +32-16-327081
Celestijnenlaan 200A, B-3001 Heverlee, Belgium       fax: +32-16-327996
Office: A04.36




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