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Subject: Re: [boost] different matrix library?
From: DE (satan66613_at_[hidden])
Date: 2009-08-19 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 (non-nrc) 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 1-3 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


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