creation of matrix valued quantities
There is a bug in the creation of matrix valued quantities. If a quantity is generated in the way
q = quantity.Function(@(t) sin(2 * pi * t, 'domain', quantity.Domain.defaultGrid));
Q(2,2) = q;
Q is mixed by empty quantities and q. Thus, the entries have different grids and a further operations as
Q.plot()
will crash. This should not happen!