Re: [ublas] determinant and norm

From: Karl Meerbergen (Karl.Meerbergen_at_[hidden])
Date: 2005-12-19 10:43:56

Eddie Vedder wrote:

>>The determinant is 
>>usually computed from the LU factorization: compute the product of the 
>>diagonal of U and you have the determinant.
>>    
>>
>
>I computed the LU factorisation of the matrix with ATLAS bindings function
>lu_factor(A,ipiv) where A holds the LU factorisation. The problem is, that
>the product of the diagonal results in a determinant with wrong sign. I
>found out, this has to do with the pivoting. How can I find out the correct
>sign of the determinant?
>
>Ed
>

I do not know the function lu_factor. Pivoting should not change the 
value of the product of the diagonal elts, unless 2x2 pivots are present 
(for symmetric matrices).

Karl