intmat name = intmat_expression ; intmat name [ rows ] [ cols ] = intmat_expression ; intmat name [ rows ] [ cols ] = list_of_int_and_intvec_and_intmat_expressions ; rows and cols must be positive int expressions.

Purpose:

defines an intmat variable.
Given a list of integers, the matrix is filled up with the first row
from the left to the right, then the second row and so on.
If the int_list contains less than rows*cols elements,
the matrix is filled up with zeros; if it contains more
elements, only the first rows*cols elements are used.