Depends on the programming language.

I bet there are shelfs full of mathematical textbooks about that question.

Damn degenerates and their hip blue jeans.

The belt and belt loops go all along the top row. If there’s only one row, the matrix can only wear a short-shorts version. There’s a crotch in each space between columns, and a leg on every column of length greater than 1.

Sparse matrices have their own special pants that are more efficient, of course.