Suppose you have four vectors (A, B, C, and D) with different lengths, you can aggregate them into one vector G as:

G= [A; B; C; D];

Then you can find the average of G as:

mean(G);

Or  just sum the components of the vectors and divide by total number of elements.

For example if you have three vectors X={4,5,6} , Y = {10, 11, 9} and  Z ={4, 3,5} .

Here, Sum= 57 and total components (n)= 9, Sum/n=6.3

you can also calculate as: For X vector, Sum/3=5, for Y, sum/3= 10, for z, sum/3= 4. Now add these numbers and divide by total number of vectors i.e.3, 19/3= 6.3.

thanks all for answering... I want to get a new vectors for the average , so I have to make the vectors same length first,for example: 

A={1,2,3,4,5}

B={1,2,3}

C={1}

then 

I want to get a G vector which represent the average as a vector not just one number, Please any assistance will be so appreciated...  

Hiba,

In that case scenario the code is:

G=[mean(A); mean(B); mean(C)];

Your 3 vectors are in different vector space to it dosenot makes any scene to take their average , but if project all them to same vector space then you can do so.

eq,

A=[1,2,3,4,5] '=> Ap=[1,2,3,4,5]'

B=[1,2,3]' => Bp=[1,2,3,0,0]'

C=[1]' => Cp=[1,0,0,0,0]'

mean([Ap,Bp,Cp],2)={1,4/3,2,4/3,5/3}.

use cells is the easiest way for different vector length

http://www.mathworks.com/help/matlab/ref/cell.html