[SciPy-user] solve for symetric matrix ?

fred fredmfp@gmail....
Thu Apr 26 08:28:50 CDT 2007


Ronan Perrussel a écrit :
> fred a écrit :
>> Joachim Dahl a écrit :
>>  
>>> if diag(A)=0 then   ei'*A*ei  = 0 so A is not positive definite.  
>>> Same goes for -A,  so A is
>>> not negative definite either.
>> h, I surely misunderstand something but what ?....
>>   
> ei is a vector of the canonical basis of R^n.
> For instance, e1 = (1, 0, ..., 0)' and e1'*A*e1 = A_{11} = 0.
> If A is positive definite, it should be stricly positive.
That's ok.
Just a typo in the (french) wiki page on positive definite matrices.

Thanks.

-- 
http://scipy.org/FredericPetit



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