# Ublas :

Subject: Re: [ublas] whole ublas matrix as vector
From: Michael Norel (minorlogic_at_[hidden])
Date: 2009-09-07 10:06:46

Sorry , i found answer on my question

norm_inf
Vector norm_inf v = maximum (abs (v [i]))
Matrix largest row sum of A, max(sum(abs(A')))

norm_1
Vector norm_1 v = sum (abs (v [i]))
Matrix largest column sum of A, max(sum(abs(A)))

--- On Mon, 9/7/09, Michael Norel <minorlogic_at_[hidden]> wrote:

> From: Michael Norel <minorlogic_at_[hidden]>
> Subject: Re: [ublas] whole ublas matrix as vector
> To: "ublas mailing list" <ublas_at_[hidden]>
> Date: Monday, September 7, 2009, 3:35 PM
> Hi All.
>
> i tried to use "norm_inf" for matrices but i get unexpected
> result
>
> //-------------------------------------------
>    Matrix m(2, 3);
>    Vector v(2*3);
>
>    for (SizeType i = 0; i < m.size1 ();
> ++ i)
>    {
>       for (SizeType j = 0; j < m.size2
> (); ++ j)
>       {
>          v (i * m.size2() +
> j) = m (i, j) = -(Real)(3 * i + j);
>       }
>    }
>
>    std::cout << m << std::endl;
>    std::cout << v << std::endl;
>
>    std::cout << norm_inf(m) <<
> std::endl;
>    std::cout << norm_inf(v) <<
> std::endl;
> //-------------------------------------------
>
> .[2,3]((-0,-1,-2),(-3,-4,-5))
> [6](-0,-1,-2,-3,-4,-5)
> 12
> 5
>
> Is it expected result? what is math meaning of norm_inf(m)
> ?
>
> Thanks
>
>
>
>
> --- On Sun, 9/6/09, Gunter Winkler <guwi17_at_[hidden]>
> wrote:
>
> > From: Gunter Winkler <guwi17_at_[hidden]>
> > Subject: Re: [ublas] whole ublas matrix as vector
> > To: "ublas mailing list" <ublas_at_[hidden]>
> > Date: Sunday, September 6, 2009, 9:11 PM
> > Michael Norel schrieb:
> > > Hi all!
> > >
> > > I still need this functionality (matrix
> expression as
> > vector expression)for intensive use of ublas.
> > >
> > >
> > Please check out the latest development version from
> SVN:
> > see

> > and have a look at
> > experimental/sparse_view.hpp, class c_array_view.
> This
> > class should
> > fulfill the immutable part of storage array concept.
> Now
> > only a class
> > fulfilling the immutable part of the vector concept
> must be
> > developed
> > which can be used to present any storage array as a
> read
> > only vector.
> >
> > > I need to
> > > 1. compare 2 matrixes with some eplison threshold
> like
> > "norm_2(m1-m2) < eps"
> > >
> > Why not using norm_inf or norm_1 for matrices?
> >
> > > 2. check if the submatrix of matrix is zero like
> > "norm_2(m1) > 0"
> > >
> > I'd also suggest to use norm_inf or even better a
> customer
> > function that
> > aborts the check at the first non-zero element.
> > > 3. find the absolute maximum element of matrix
> like
> > norm_inf(m1)
> > > and many others, where m1 and m2 is matrix
> > expressions.
> > >
> > >
> > Could you prepare a list of the most used matrix
> functions?
> > Maybe there
> > are others interested. Then we could easily add a
> > matrix-tools header
> > which contains such methods.
> >
> > There is a trac for boost: https://svn.boost.org/trac/boost/
> >
> > Here you can view, comment and create new tickets.
> Feel
> > free to create a
> > feature request for uBLAS. Try to add an example or
> > pseudo-code to
> > express the expected usage.
> >
> > > Where can a i post the functionality request for
> such
> > adaptor?  Or it is realy the right way to implement
> it
> > myself?
> > >
> > The quickest way is always do it on yourself and to
> post
> > the patch, an
> > example and a unittest here. Then I can review the
> code and
> > commit it to
> > the repository.
> > _______________________________________________
> > ublas mailing list
> > ublas_at_[hidden]

> > Sent to: minorlogic_at_[hidden]
> >
>
>
>
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> Sent to: minorlogic_at_[hidden]
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