# [Numpy-discussion] Re : Array of matrices - Inverse and dot

Jean-Baptiste Rudant boogaloojb@yahoo...
Mon Jan 26 09:25:54 CST 2009

```Thank you, but my example was bad. I have to deal with matrices which can be 100*100.

________________________________
De : David Cournapeau <cournape@gmail.com>
À : Discussion of Numerical Python <numpy-discussion@scipy.org>
Envoyé le : Lundi, 26 Janvier 2009, 16h18mn 33s
Objet : Re: [Numpy-discussion] Array of matrices - Inverse and dot

On Mon, Jan 26, 2009 at 11:59 PM, Jean-Baptiste Rudant
<boogaloojb@yahoo.fr> wrote:
> Hello,
> I would like to operate in an easy and efficient way (without python
> loop) with arrays of matrices.
> Suppose a and b are some arrays of N1*N2 matrices of size 3*3, I would like
> to calculate  inv_a and dot_ab, which would be arrays of N1*N2
>  (3*3)-matrices, such as :

If you only care about 3*3 matrices, I would consider using
"developed" formula of a 3x3 matrix inverse coded in numpy. numpy.inv
will be quite slow for such small matrices anyway (all the machinery
to call the underlying C code being almost certainly the bottleneck).

David
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