Creating two vectors from one.

Hi I have a vector;

x = [2 4;3 -8; 1 2; 2 4;]

I need to produce two vectors like the ones to the left and right below. To get the vector on the right it is x_r = [2*-8 3*2 1*4] and same process for left(x_l) the arrows show what needs to be multiplied by what.

If the number of rows (columns will always = two) increase or decrease or the numbers change I need to account for this. Is there a way where I can do this by vectorization or will I be stuck with loops.

Thanks,

Answer 1

[Mischa Kim]

Giuseppe, use

 xr = x(1:end-1,1).*x(2:end,2)
 xr =
   -16
     6
     4

and equivalent for the other calculation.

[Giuseppe]

Thank you Mischa. You are a legend!

Answer 2

[Chandrasekhar]

x = [2 4;3 -8; 1 2; 2 4];
[m,n]=size(x);

for i= 1:m-1
    a(i,1) = x(i,2)*x(i+1,1);
    a(i,2) = x(i,1)*x(i+1,2);  

end

[Giuseppe]

Thanks for the contribution. I really appreciate it.