A general update:
I've started to migrate the stand alone demo-code in Eigen's in the following fork:
don't pay attention to the current naming, I'll do search/replace once we have truly settled down them.
PLEASE share your opinion!
For the record, we have to agree on at least 4 names:
1 - one to denote a kind of alias to std::integral_constant<int,N>, the current best choice seems to be: fix<N>
2/3 - a pair of names to denote an arithmetic sequence starting at position i, with increment d, and either an inclusive upper bound j or a size n. The current best candidates are:
* seq(i,j,d) / seqN(i,n,d) or seqn(i,n,d)
* aseq(i,j,d) / aseqN(i,n,d) or aseqn(i,n,d)
* range(i,j,d) / span(i,n,d)
With the 'n' vs 'N' suffix variations this makes 5 options. My current personal preference go to seq/seqN.
4 - A pseudo "keyword" to denote all elements, aka ':' in MatLab. Two candidates so far: All and all
FYI, the current fork already supports various ops, as shown in the testing code below.
There is still a lot of work to do for a more seamless and efficient integration, in particular I have to figure out a way to unify this API with Eigen::Block/Eigen::MapBase. There are many approaches, including:
1 - return a Block<> _expression_ if the arguments are compatibles (unit steps)
2 - make IndexedView inherits MapBase when possible, and cleanup redundancies by writing Block<> on top of IndexedView
I'll probably try option 1 first. Less risky regarding regressions in the current Block.
using namespace Eigen;
using namespace std;
#define PRINT(X) cout << #X << "\n" << X << "\n\n"
for(int i=0; i<10; ++i)
for(int j=0; j<10; ++j)
A(i,j) = i*10+j;
cout << A << "\n\n";
ArrayXd eia(10); eia.setRandom();
Array4i eii(4); eii << 3, 1, 6, 5;
valarray<double> vala(10); Map<ArrayXd>(&vala,10) = eia;
valarray<int> vali(4); Map<ArrayXi>(&vali,4) = eii;
vector<int> veci(4); Map<ArrayXi>(veci.data(),4) = eii;
PRINT( A(3, range(9,3,-1)) );
PRINT( A(span(2,5), range(9,3,-1)) );
PRINT( A(span(2,5), 5) );
PRINT( A(span(last,5,-1), range(2,last)) );
PRINT( A(eii, veci) );
PRINT( A(eii, all) );
// takes the row numer 3, and repeat it 5 times
PRINT( A(span(3,5,0), all) );