Subject: Re: [boost] Preliminary submission: generic linear algebra algorithms library Boost LA
From: Thomas Klimpel (Thomas.Klimpel_at_[hidden])
Date: 2009-10-23 06:28:53
Emil Dotchevski wrote:
> Thomas Klimpel wrote:
> > Providing wrappers for T[D1][D2][D3] and T[D1][D2][D3][D4] , ..., T[D1][D2][D3][D4][D5][D6][D7][D8][D9] might also be useful sometimes (and the code generators might help here...), but this is the question of the scope of the library again.
>
> I'm not sure why we're talking about 3D arrays,
> those can't possibly represent vectors or matrices.
I completely agree that a 3D array can't possibly represent vectors or matrices. The wrapper for "T[D1][D2][D3]" would be "la::ten3<T, D1, D2, D3>", and its traits would be ten3_traits, and the wrapper for T[D1][D2][D3][D4][D5][D6][D7][D8][D9] would be "la::ten9<T, D1, D2, D3, D4, D5, D6, D7, D8, D9]>". The reason we are talking about 3D arrays is that the C++ language has fixed-size higher dimensional multi_arrays, but only very limited language support for them.
Now I have no strong opinions about whether there is a need for such wrappers or not. I searched my source code for occurrences of higher dimensional fixed size arrays, and found only very few occurrences. The occurrences were of the type float points[2][2][2] and float derivatives[2][2][2][3], and represented values in the corners of the unit-cube.
Just tell me that higher dimensional tensors are clearly out of scope of the library, and everything is fine.
Regards,
Thomas