[boost] New version of cvalarray in the vault

From: Mike Tegtmeyer (tegtmeye_at_[hidden])
Date: 2007-06-18 12:29:28

All,

An updated version of cvalarray has been posted to the vault. Although the 
original purpose was to mimic std::valarray as much as possible, features 
that address the criticism of std::valarray in issue 93 (and others) of 
the c++ working groups have been added. Since there are few specifics in 
this area, it would be nice to hear the community weigh in on some of the 
design decisions. In no particular order:

- non-member operations on cslice_array and cindirect_array are now 
defined: ie

res[cslice<0,4,3>()] = (foo[cslice<1,4,3>()] * bar[cslice<2,4,3>()]);

expression templates are used to eliminate temporaries and operations are 
unrolled for small N

- operator[] is defined for both cslice_array and cindirect_array. Not so 
sure about this one. I can see a valid use case (computed indirect 
indices) but if the purpose of std::slice_array and std::indirect_array is 
to be transparent to the user, this is directly a violation of that. I can 
go either way if folks don't like it.

- member computed assignment for cslice_array and cindirect array are 
added for all: ie

T foo[N] = {...};
cvalarray<T,2*N> bar;

bar[cslice<1,N,2>()] += foo;

In addition it is now possible to have a computed assignment of another 
cslice_array or cindirect_array: ie

foo[cslice<1,2,3>()] += bar[cslice<3,2,1>()];

or

cvalarry<size_t,2> indirect;
foo[cslice<1,2,3>()] += bar[indirect];

expression templates are used to eliminate temporaries and operations are 
unrolled for small N

- transcendental operations are now defined for cslice_array and 
cindirect_array: ie

cvalarray<float,10> foo = cos(bar[cslice<2,10,3>()]);

does not result in an unnecessary temporary creation.

The documentation and test cases have been updated for the above changes.

Mike