[Numpy-discussion] A bug in scipy.linalg.lu_factor?

Nils Wagner nwagner at iam.uni-stuttgart.de
Thu Jan 25 12:37:01 CST 2007


On Thu, 25 Jan 2007 16:06:23 -0200
  "Paulo J. S. Silva" <pjssilva at ime.usp.br> wrote:
> Hello,
> 
> I am trying to write some unit tests to my new 
>"Automatic matrix" code
> and I think I bumped into a bug in 
>scipy.linalg.lu_factor. If you give a
> matrix to it, it doesn't honor the overwrite_a option:
> 
> In [1]:import numpy as num
> 
> In [2]:M = num.mat(num.random.rand(2,2))
> 
> In [3]:print M
> [[ 0.33267781  0.2100424 ]
> [ 0.61852696  0.32244386]]
> 
> In [4]:import scipy.linalg as la
> 
> In [5]:LU, P = la.lu_factor(M, overwrite_a=0); print M
> [[ 0.33267781  0.63136882]
> [ 0.61852696 -0.06807478]]
> 
> In [6]:LU, P = la.lu_factor(M, overwrite_a=0); print M
> [[ 0.63136882  0.52691517]
> [-0.06807478  0.6543966 ]]
> 
> As you can see the matrix is changed by calling the 
>function.
> 
> can anyone confirm this? I am running numpy 1.0.1 and 
>scipy 0.5.2.
> 
> Best,
> 
> Paulo
> 
Hi Paulo,

I can confirm this bug.

1.0.2.dev3511
0.5.3.dev2560

Nils

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