[SciPy-User] [SciPy-user] Covariance matrix

Johannes Eckstein eckjoh2@web...
Mon Feb 13 02:59:20 CST 2012

Hi All,
I have an additional question to that below.

how can I do a matrix multiplication of a matrix X with shape: (240001, 4)

M = X * X.H

when I do this I get the following:
     return N.dot(self, asmatrix(other))
ValueError: array is too big.

What is the best way to avoid this error?

Thanks in advance,

> On Fri, Feb 10, 2012 at 9:11 AM, suzana8447 <k-assem84@hotmail.com 
> <mailto:k-assem84@hotmail.com>> wrote:
>     Hello every body,
>     I am using least square fit to fit some function to a given data.
>     The fit is
>     perfect with leastsq. Now, I need to calculate the covariance
>     matrix whereby
>     the diagonal terms represent the variances for the parameters.
>     I need to know, if possible, how to extract the covariance matrix from
>     leastsq. If there is no way to extract it, Are there any good
>     methods that
>     can be used to calculate the covariance matrix with high precision?
> If you pass the optional argument full_output=1 when calling leastsq 
> the (scaled) covariance matrix will be returned in the slot after the 
> solution. It needs to be multiplied by an estimated measurement 
> variance determined from the residuals or by some other method. The 
> documentation isn't quite right on that score, it says standard 
> deviation. The computation of the covariance probably isn't the best 
> numerically as its triangular factors are multiplied before inversion, 
> rather than vice-verse. Patches welcome ;)
> Chuck
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