[Numpy-discussion] Inaccuracy in documentation of np.linalg.pinv

Hao Xiong hao@biostat.ucsf....
Fri Mar 11 20:50:55 CST 2011


Hi Ralf,

I am happy to edit it, although I will have to do it later as I won't
have much free time recently.

I have registered as haoxiong on docs.scipy.org and would like
to request edit rights to the pinv page.

Thanks,
Hao


On 03/09/11 04:16, Ralf Gommers wrote:
> Hi Hao,
>
> On Wed, Mar 9, 2011 at 9:01 AM, Hao Xiong <hao@biostat.ucsf.edu> wrote:
>> I think the documentation for np.linalg.pinv contains some inaccuracies.
> Thanks for your comments. Are you interested to make some improvements
> yourself? It's quite easy to do on the numpy doc wiki:
> http://docs.scipy.org/numpy/docs/numpy.linalg.linalg.pinv/
> Just ask for edit rights on this list after registering a username.
>
> Cheers,
> Ralf
>
>
>> Most importantly, Moore-Penrose is not defined by the solution to the
>> least-square
>> problem. It was defined by the unique solution to 4 equations. Since SVD
>> can be easily shown to satisfy the same 4 equations, it is the
>> Moore-Penrose inverse.
>>
>> Another way that definition is wrong is that the least-square problem
>> does not have to have
>> unique solution. In fact, it can have infinitely many. In this case,
>> Moore-Penrose is the minimum
>> norm solution.
>>
>> All of this is discussed in the Matlab documentation of pinv, which is
>> very good.
>>
>>
>> Hao
>> _______________________________________________
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>>
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