>>> from matrius import Matriu, enum_matriu

>>> m = Matriu(2, 3)
>>> m[0, 0] = 3
>>> m[1, 1] = -5
>>> list(m)
[3, 0, 0, 0, -5, 0]
>>> list(enum_matriu(m))
[((0, 0), 3), ((0, 1), 0), ((0, 2), 0), ((1, 0), 0), ((1, 1), -5), ((1, 2), 0)]