
Boost : 
Subject: Re: [boost] different matrix library?
From: DE (satan66613_at_[hidden])
Date: 20090819 14:11:00
> i got somewhat unexpected results
> i reimplemented 'matrix' in terms of nrc
> here are results
> 1. a small mixin to vector operations
> disadvantage is ~10%  predictable
> (here by advantage i mean ratio (old_time  nrc_time)/old_time
> since i assume that nrc would outperform old (nonnrc) code (should
> be nrc_time<old_time, then ration is >0)
> if the ratio is negative then it is actually a disadvantage
> value of ratio is in % for convenience)
> 2. intensive matrix operations (+* etc.)
> advantage is roughly zero  predictable
> 3. matrix multiplication
> advantage is roughly zero for best implementation  predictable
> (see mul.png)
> 4. matrix inversion (inplace, full pivoting)
> _advantage_ is ~15%  totally unpredictable
> (see inv.png)
> actually it's difficult for me to explain the reason
> since it implements full pivoting maybe acceleration of the search
> process defeats the slowness of reducing cycles
> or maybe i made a mistake
> however i can explain cases 13 disadvantages by the involvement of
> additional allocation/deallocation and setup process i'm still
> wondering about the latter case
> but i consider an invertion such an unwanted corner case and that's
> why i suggest to implement computed indeces for 2d case
> however for you, joel, there is nothing to bother since your point is
> perfectly motivated
here is ms excel file
 Pavel
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk