Re: [ublas] How to understand the meanings of the member function index1() and index2() in the iterator of compressed_matrix

Subject: Re: [ublas] How to understand the meanings of the member function index1() and index2() in the iterator of compressed_matrix
From: Rutger ter Borg (rutger_at_[hidden])
Date: 2010-11-12 09:32:13

On 2010-11-12 14:56, 魏华祎 wrote:
> Hi,  everyone,
>
>
>     Please  tell me how to understand the meaning of the return value
> of the following function members  in iterators class of
> compressed_matrix class:
>
>      ublas::compressed_matrix<double, ublas::row_major>  ::iterator1.index1();
>      ublas::compressed_matrix<double, ublas::row_major>  ::iterator1.index2();
>
>      ublas::compressed_matrix<double, ublas::row_major>  ::iterator2.index1();
>      ublas::compressed_matrix<double, ublas::row_major>  ::iterator2.index2();
>
> I can't make sure about it.  Then if replace the ublas::row_major by
> ublas::column_major?
>
> Thanks!
>
>
> Huayi
>

Hello Huayi,

everything with number N represents the N-th coordinate of the index of 
the object. In numeric_bindings, we called this number the "addressing 
index".

So, iterator1 will iterate over the first coordinate of a matrix, i.e., 
its rows. Irrespective of the data order of the matrix. I guess the 
.index1 and .index2 will give you the actual coordinate values of the 
entry you are visiting.

Hope this helps,

Rutger