using 3x1 matrix to make 21x1 matrix

I have built the 3x1 matrix below

EA = 1; 
h = 1; 

P = 1
FF = @(xi) (0.5*xi).*(xi-1)
f(1,1) = P*h/2*quad(FF,-1,1)

FF = @(xi) (1-xi.^2)
f(2,1)= P*h/2*quad(FF,-1,1)

FF = @(xi) (0.5*xi).*(xi+1)
f(3,1) = P*h/2*quad(FF,-1,1)

I want to use the 3x1 matrix to create a 21x1 matrix following the pattern below

the overlapped elements should be added. I want to use a for loop to create the matrix unless there's another method

[Walter Roberson]

Is it correct that after the first entry, it just keeps repeating [f12; f13+f11] over and over?

[Shubham Gupta]

Do you want something like this?

f_out = [f(1);repmat([f(2);f(2)+f(3)],[10,1])]

Answer 1

[Prabhan Purwar]

Hey,

Following command may help:

f_out = [f(1);repmat([f(2);f(1)+f(3)],10,1)];

Could you elaborate more if this is not the desired output?