On 02/16/2012 02:42 AM, Bjoern Andres wrote:
Hi everyone,
I have written a header for runtime-flexible multi-dimensional views and arrays and would love to get comments and feedback from the boost community:
tutorial code : http://tinyurl.com/7hdldc9 main website : http://www.andres.sc/marray.html doxygen reference doc: http://www.andres.sc/marray/doc/index.html git repository : https://github.com/bjoern-andres/marray tech report : http://arxiv.org/pdf/1008.2909v1
Unlike in Boost.MultiArray, the dimension of arrays is not a template parameter in Marray.
In Boost.MultiArray, the dimension is not a template parameter; the number of dimensions is. I assume you always use the maximum number of dimensions, and treat arrays of size N*M the same as arrays or size N*M*1*1*1*1
Other features include
- runtime-flexible dimension, shape, size and indexing order (first or last coordinate major order)
- arithmetic operators with automatic type promotion and expression templates.
This should be decoupled from the container itself. Algorithms and containers are different things. If you're doing expression templates, you should re-use Boost.Proto to have a proper framework to deal with expression trees. And if you're supporting arithmetic operators, it will be expected that you generate high-performance parallel code (like Blitz++, Eigen, or NT2 -- I am the author of the latter). I'm not sure type promotion is such a good idea.
- access to entries via coordinates, scalar indices and STL-compliant random access iterators.
I find it confusing that iterators flatten the data. I'd rather they iterate on the external dimension. If you want to iterate over flattened data just make a view with a flattened shape and iterate that. Also if you support 1D and nD access, why not also support 2D or 3D access within a 4D array? Something else, what we do in NT2 is that we use an iliffe index as described in the NRC (Numerical Recipes for C) book. This allows us to make a view that extracts an arbitrary rectangle or hypercube and to add padding between lines without extra modulo operations. Do you use something like that as well?