I'm not sure what assume(x>0) has to do with anything, because you are working with the variable n.
But why have you not just put a while loop around it? For example, this seems to work:
while n ~= 1
if mod(n,2) == 0
n = n/2
else
n = 3*n+1
end
end
Note that you CANNOT use a test like
if n=1
because n=1 is an assignment operator, NOT a test for equality. It is not necessary anyway, since you just want that test in the while statement anyway. I'm not sure what you intend to do with the sequence produced. Your code will just dump it to the command window.
Oh, learn to use semicolons on your lines. But I suppose if your goal is to just dump n into the command window, then it works perfectly well.
What you need to decide is what you want out of this loop. Do you just want to count how many iterations it takes until the iterations land at 1? That is a fairly common goal, to count the iterations, since the Collatz conjecture is that all sequences will eventually terminate there. Or, you can store all the iterations for any given sequence. But only you know what you want to do here.
