If you could give us your exact code you are trying now, that would be really helpful. zeros(your matrix size) should work fine no matter what toolbox you have. Unless your question is about having an unknown number of output variables.
If you know the number of output variables, like if I wanted to find the size of a 2-d matrix I would do something like this [numRows, numCols]=size(twoDmatrix);
Similarly, you can do that for output with multiple variables.
If you don't know the # of output vars, it gets more complicated, but I remember somehow being able to capture everything in a cell array, I think using the deal function or something like that.
