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From: Michele De Stefano (micdestefano_at_[hidden])
Date: 2008-01-14 02:37:31

I answer points 1 and 2. For what regards point 3, I have to say that I've
never used the scalar matrix ... may be someone else can answer.

1) In uBLAS, as in any other matrix computational libray, there is no
function to perform the inverse explicitly. If you need the inverse to solve
a system, you must exploit numerical solvers (LU decomposition, for
example). There are some LAPACK bindings around ... I don't remember where
to download them ... try the "Effective uBLAS" link.

2) norm_1 performs the computation of the L1 norm of a vector, not simply
the sum of its elements. The L1 norm, by definition, is exactly the sum of
absolute values (see Wikipedia or MathWorld).


2008/1/8, nchygy <nchygy_at_[hidden]>:
> Hello,
> I have several question on using ublas.
> 1. In ublas is it provide any function or method for matrix to calculate
> the inverse?
> 2. In the overview of ublas "norm_1 (x)" has been described to be an
> function to calculate "sum xi" However when i use it calculate the sum of an
> vector x=(87, -32,-34)
> it gives an result 153, that is an wrong number. It seems the norm_1
> calculate the sum |xi|
> Is it the truth?
> 3. I found it is difficult to use the scalr matrix ,because it can not be
> used to multiply with other matrix.(it show me error, when i tring to do so
> using the function "prod").
> Best regards
> Yang GAO
> --
> ¸ßÑï
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