taking a crosssection of a 3-D array

[bearophile]

Andrew:
> So, how do I take a cross section of a 3-D array.  Basically I want to be able to take a 2D matrix from a 3-D array.
> auto m = a[][n][];

Languages (or libraries) like matlab and NumPy allow to slice nD arrays like you say, using a very compact syntax, but currently the D1/D2 languages aren't designed for people that perform "serious" numerical computations, so it doesn't offer built-in ways to slice nD arrays.
So you can write a function template that performs such slices, that insides copies items.

Currently D1/D2 1D arrays are 2-structs that point to a memory zone, so 2D arrays are 2-structs that contain a pointer to a memory zone of structs that contain pointers to memory zones of the "rows" of data.

Bye,
bearophile