Your dimensions were all messed up: note that , is used to concatenate the columns horizontally (you used ; which concatenates vertically), and you tried to specify the output column as the input argument to each function (but this should simply be the dimension to work along on the input matrix):
function S = simple_stats(N)
S = [mean(N,2),median(N,2),min(N,[],2),max(N,[],2)];
and tested:
>> X = randi(9,7)
X =
8 5 8 1 6 8 7
9 9 2 8 2 7 8
2 9 4 9 7 3 2
9 2 9 7 1 9 5
6 9 8 7 3 1 5
1 9 9 7 1 4 6
3 5 6 4 1 4 7
>> simple_stats(X)
ans =
6.1429 7 1 8
6.4286 8 2 9
5.1429 4 2 9
6 7 1 9
5.5714 6 1 9
5.2857 6 1 9
4.2857 4 1 7
Hint: don't just write code and hope that it works. Write and check it as you write it. Check every line and every command, that it is doing exactly what you need it to do. Beginners often seem to think that a command is doing something, but never even bother to check. You could easily have run those functions (mean, etc) in the command windows with small matrix, and discovered that the output was not as you expected...
Also, learn to read the documentation. That would also have told you that you were using them incorrectly.
