[Numpy-discussion] Question on LinAlg Inverse Algorithm

Mark Janikas mjanikas@esri....
Tue Aug 30 18:34:10 CDT 2011


When I export to ascii I am losing precision and it getting consistency... I will try a flat dump.  More to come.  TY

MJ

-----Original Message-----
From: numpy-discussion-bounces@scipy.org [mailto:numpy-discussion-bounces@scipy.org] On Behalf Of Mark Janikas
Sent: Tuesday, August 30, 2011 4:02 PM
To: Discussion of Numerical Python
Subject: Re: [Numpy-discussion] Question on LinAlg Inverse Algorithm

Working on it... Give me a few minutes to get you the data.  TY!

MJ

-----Original Message-----
From: numpy-discussion-bounces@scipy.org [mailto:numpy-discussion-bounces@scipy.org] On Behalf Of Christopher Jordan-Squire
Sent: Tuesday, August 30, 2011 3:57 PM
To: Discussion of Numerical Python
Subject: Re: [Numpy-discussion] Question on LinAlg Inverse Algorithm

Can you give an example matrix? I'm not a numerical linear algebra
expert, but I suspect that if your matrix is singular (or nearly so,
in floating point) then any inverse given will look pretty wonky. Huge
determinant, eigenvalues, operator norm, etc..

-Chris JS

On Tue, Aug 30, 2011 at 5:48 PM, Mark Janikas <mjanikas@esri.com> wrote:
> Hello All,
>
>
>
> Last week I posted a question involving the identification of linear
> dependent columns of a matrix. but now I am finding an interesting result
> based on the linalg.inv() function. sometime I am able to invert a matrix
> that has linear dependent columns and other times I get the LinAlgError().
> this suggests that there is some kind of random component to the INV
> method.  Is this normal?  Thanks much ahead of time,
>
>
>
> MJ
>
>
>
> Mark Janikas
>
> Product Developer
>
> ESRI, Geoprocessing
>
> 380 New York St.
>
> Redlands, CA 92373
>
> 909-793-2853 (2563)
>
> mjanikas@esri.com
>
>
>
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