When using a dynamic matrix, there is no clear way to extend a matrix not with copies of a single element, but with a vector (like with insert_row or insert_column) or with a matrix (counterpart to insert_rows or insert_columns). In fact judging by the names, I thought that they used a vector and matrix respectively and not a single value.

This isn't mentioned at all in the reference and I haven't found anything in the API. Is there any reason that concatenation isn't supported when insert_row and insert_column exist? My current solution is to create a vec of vectors and use the from_columns constructor.