[ublas] slice iterators are indexed iterators

Subject: [ublas] slice iterators are indexed iterators
From: Neal Becker (ndbecker2_at_[hidden])
Date: 2008-10-21 08:57:38

It seems that basic_slice iterators are indexed, they store an integral index and dereference looks like:
                return (*this) ().start () + it_* (*this) ().stride ();
 
This seems to kill performance.  Is there any good reason why slice iterators could not be based on pointers?  If it were, the most common use, which would iterate using 'it++' should be faster.