Do we need Mat, Vec, TMmat, Diag, Sym and other matrix types?

[9il]

On Tuesday, 13 March 2018 at 05:36:06 UTC, J-S Caux wrote:
>
> Your suggestion [4] that matrix[i] returns a Vec is perhaps too 
> inflexible. What one needs sometimes is to return a row, or a 
> column of a matrix, so a notation like matrix[i, ..] or 
> matrix[.., j] returning respectively a row or column would be 
> useful.

auto row = matrix[i]; // or matrix[i, 0 .. $];
auto col = matrix[0 .. $, j];