on 14.08.2009 at 20:45 joel wrote :
internally i alwayse use () but [] are provided for users' convenience It's really not needed. operator(i) is the same semantically and I don't think any STD concept require []. Having matrix be real function object is also a good way to use htem more generically. i see no contra in you words so i don't get why to drop nice subscript operator[]
but they are handled differently (different public interface) vector is modeled after std::valarray (everybody knows about valarray) and matrix is just a generalization of std::valarray behavior oh and vector is a column-vector Just don't name it vector then. In lin. Alg. a vector is a matrix with one dimension equal to 1. if not, ppl will wonder why matrix*vector doesn't mean what they think it does. well i always thought that 'vector' is a column vector if not stated explicitly otherwise for me it's obvious so (matrix*vector) is obviously a vector (column vector)
You should have one matrix class whose tempalte parameters allow for customization. Want a matrix with static data : matrix<float, settings<static_> > i thought about that and i agree that your variant is a better idea but i have not started to refine the code yet to my flavor it must be something like
matrix<double, some_container_like_type<double> > //^^ double? or even matrix<double, some_container_like_template_type> //template template parameter is used
NRC allocation states that a array of N dimension is stored as N array of pointers, each pointinng to sub-element of the next one, the last one being a large, monolithic contiguous array of data. This allow for N-dimensionnal acces via chains of [] and ensures cache locality at the latest level. It's easy to write, can be recursively extended for arbitrary dimension number and ease the writings of code that requires you to extract or work on complex sub-array. performances of access is roughly the same that T* (within a 2% margin). this requires to have an iterface that takes smthg lika boost::array for handling set of dimensions and indexing. sample 2D code here : http://codepad.org/nDy8z2iG of course this has to be hidden in the implementation. sounds cool but i have no any tasks with >2 order involved so i was not even considering i will think about it is it a must have feature in your opinion?
i've heard and forgotten i've seen and memorized i've done and understood ...or something like thi which means ? which means that if i have not done that i have not understood it
-- Pavel