Re: [ublas] Several questions

From: Gunter Winkler (guwi17_at_[hidden])
Date: 2008-05-29 17:13:15

Am Donnerstag, 29. Mai 2008 10:59 schrieb Hongzheng Wang:

> In fact, both this question and the above one come from my experience
> using std::valarray.  I find it is a convenient and productive
> mechanism to bring in the concepts of 'general slice', 'indirect
> array' and 'masked array' etc.  For example, suppose idx is an index
> array, say, idx[0]=5, idx[1]=6, idx[2]=10, then something like
> indirect subsets can be expressed as va[idx].  When I come to uBLAS,
> I notice that there are only slice and range. 

there is also indirect_array and the corresponding vector and matrix 
proxies. Here you prepare the list of indices in the index_array object 
and then create a (AFAIR) vector_indirect(v, ia)

mfg
Gunter