Re: [boost] [rfc] A light weight statically typed matrix template class (again?)

From: Andreas Harnack (ah.boost.04_at_[hidden])
Date: 2007-12-06 17:07:33

Jens Seidel schrieb:
> Hi,
> 
> a few days ago I started exactly as you described (except that I used
> old style for loops instead of STL stuff :-) a TinyDenseMatrix class
> to implement the Moore Penrose pseudo inverse for real tiny matrices
> (4 x n, n<20).
> 
> A very big disadvantage is using fixed dimensions. There is no need for
> memory allocation in this case but it restricts the usage dramatically!
> 
> Nearly always the dimensions are variables, there are only a few rare
> cases where you know these before. So how about making N and M variables
> and providing one or two good memory allocators?
> 
>>          T* data() { return &**m; }
> 
> Why not &m[0][0]?

Just a matter of taste, I guess. Actually I'm not even sure yet 
that it's wise to use a two dimensional array at all. T m[M*N] 
would work equally well and since there's no interface yet that 
relies on that structure, the latter might even be the simpler 
approach. The two-dimensional array just felt to be more 
'natural' for a matrix. (whatever that means :-) )

But thanks for your support,
Andreas

>> The advantage of this approach is its simplicity, in fact, it's
> 
> Right, I wrote such stuff already multiple times even if I care normally
> about sparse matrices with dimensions > 1 000 000.
> 
> Jens
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