Re: [ublas] Matrix with vector interface.

Subject: Re: [ublas] Matrix with vector interface.
From: Gunter Winkler (guwi17_at_[hidden])
Date: 2012-09-17 15:25:45

Hello,

Am Monday 17 September 2012 schrieb Joaquim Duran:
> Dear all,
> 
> My name is Joaquim Duran. I'm new to this mail list.
> 
> I'm using ublas for signal processing and I'm interested that the
> matrix have a similar interface to a vector, using a proxy, to apply
> algorithms designed for vectors. To get an idea, if the element of a
> vector is a double, then the element of a row facade is a column. If
> this possible to get this behavior using existing proxies?

Why not using a set of vectors and a matrix view of them?

ublas::generalized_vector_of_vector<
  double, 
  ublas::column_major,
  ublas::vector<ublas::vector<double> > > gvov;

this class has a data() function which returns a reference to the 
storage array (which is a vector<vector<double> >) 

So you could use gvov.data().begin() as an iterator of vectors.

see 
http://www.boost.org/doc/libs/1_51_0/libs/numeric/ublas/doc/html/classboost_1_1numeric_1_1ublas_1_1generalized__vector__of__vector.html

(Additionally you get a very fast swap() of column references compared 
to swapping all the elements)

Alternatively you could sort the indices of the columns instead of the 
real columns and use the ublas::matrix_indirect view for further 
computations.

see 
http://www.boost.org/doc/libs/1_51_0/libs/numeric/ublas/doc/html/classboost_1_1numeric_1_1ublas_1_1matrix__indirect.html#_details

mfg
Gunter