MATLAB: How to create a vector from two or three point

vector

a) A(1,2) B(6,3) C (1,5) b)A(5,9,8) B(7,5,4) C(5,7,8) How to create vector AB and AC ?

A = [1,2]
B = [6,3]
C = [1,5]
AB = B - A
AC = C - A

The same with three points

This works:

A = [1 2 3 4];
B = [5 6 7 8];
C = reshape([A; B], [], 1)';
C =
     1     5     2     6     3     7     4     8

A.a = 1;
A.b = 2 ;
A.c = 3;
save('new_c', '-struct', 'A', 'c')