Find the average of each row, ignore the first column

This is pretty straight foward, probaly something small I'm missing but as the title says, mean of each row starting at element 2. I'm getting a 3 by 1 array when i should be getting a 4 by 1 sized array. So whats wrong with my code?

load C.dat
A = C(:,2:end);
Cave= mean(A)';

[Riccardo Scorretti]

Which is the size of C?

[Eric Brown]

C is a 2 dimensional array

Answer 1

[Voss]

Let me make up a matrix C

C = (1:4)+[1;2;3;4]*10

C = 4×4

11 12 13 14 21 22 23 24 31 32 33 34 41 42 43 44

By default, mean operates along the first dimension, so this

A = C(:,2:end);
Cave= mean(A)'

Cave = 3×1

27 28 29

is taking the mean of each column of A, i.e., the mean of columns 2 through 4 of C. I imagine you intended to do this

A = C(:,2:end);
Cave= mean(A')'

Cave = 4×1

13 23 33 43

But a more direct way is to specify the dimension along which mean should operate. In this case, dimension 2 to operate along the rows

Cave = mean(C(:,2:end),2)

Cave = 4×1

13 23 33 43

[Eric Brown]

I tried doing it the way you did in your last example but couldn't figure out the syntax of it so i gave up on that approach and did it the less effient way. Thank you for your help and explanation.

[Voss]

You're welcome!