[SciPy-user] Inverse of complex matrix

Nils Wagner nwagner@iam.uni-stuttgart...
Sat Nov 10 01:54:17 CST 2007


On Sat, 10 Nov 2007 14:16:06 +0800
  "Roger Herikstad" <roger.herikstad@gmail.com> wrote:
> Dear scipy users, I am trying to invert a 12 by 12 
>complex matrix R using
> scipy.linalg.inv(), but the round-off errors seem a bit 
>too big. If I do
> scipy.dot(Ri,R), the first row of the resulting matrix 
>looks like this:
> 
> array([ 0.953125  +0.j        ,  0.06542969+0.01171875j,
>        0.08154297+0.15234375j, -0.078125  -0.09375j   ,
>        0.19140625-0.0859375j ,  0.08203125+0.140625j  ,
>       -0.08398438+0.0078125j , -0.02539062-0.03125j   ,
>       -0.06738281+0.015625j  , -0.04736328+0.15820312j,
>       -0.09057617+0.02832031j,  0.109375  -0.0625j    ])
> 
> 
> Is this normal? Inverting a 2x2 matrix produces the 
>expected result. I've
> attached a pickle of my matrix. Thanks!
> 
> ~ Roger
  
It depends on the condition number of your matrix.
Did you compute the singular values of the matrix ?

Please can you send me your test matrix in matrixmarket
format off-list.
io.mmwrite

Nils


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