function c = collatz(n)
%function c = collatz(n)
%
%  Joe Student, ID 123456
%
%  Computes the Collatz sequence for a given starting value
%
%  if n is even, divide it by 2
%  if odd, triple it and add 1
%  if n equals 1, stop
%
%  Input
%     n -- starting value (positive integer)
%
%  Output
%     c -- results, sequence of values starting with n, ending with 1
%
error(nargchk(
if n <= 0
    error(
end
if floor(n) ~= n
    error(
end
c = n;
toobig =   ;
while n > 1
    if mod(n,2) == 0
        n = 
    else
        n = 
    end
    if n > toobig
        c = [c inf];  %% set last result = inf and bail out
        break
    end
    c = [c n];
end