Re: [ROOT] means from TPrincipal

From: Eddy Offermann (eddy@rentec.com)
Date: Tue Apr 08 2003 - 03:26:26 MEST


Hi Michael,

Maybe give us some more information about how you add the data.
Is it through AddRow(x) where x is an array of 2 ?
If so, what did you do in case of N=3 ?

Eddy
> 
> Dear roottalk:
> 
> I am using TPrincipal for a 2D array. 
> 
> If I init TPrincipal as 
>  TPrincipal * principal = new TPrincipal(2,"N");
> then the first mean is incorrect.  If I init it as 
>  TPrincipal * principal = new TPrincipal(3,"N");
> then you can see what is happening:
> 
> 
>  Variable #  | Mean Value |   Sigma    | Eigenvalue
> -------------+------------+------------+------------
>            0 |  1.522e+04 |   2.21e-11 |     0.5404 
>            1 |    0.01277 |      1.031 |     0.3331 
>            2 |    0.01511 |       1.06 |     0.1265 
> 
> where the correct means are,
>  mean 1 = 0.0127681 mean 2 = 0.0151134
> 
> bug, or am I incorrectly using this class?
> 
> thanks,
> Michael Gold
> 
> 
> 



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