[Linear Algebra] Matrices and Vectors

Matrices are 2-dimensional arrays:

It's a 4*2 matrix

 

1 column's matrice is called Vector;

 

 

% The ; denotes we are going back to a new row.
A = [1, 2, 3; 4, 5, 6; 7, 8, 9; 10, 11, 12]

% Initialize a vector 
v = [1;2;3] 

% Get the dimension of the matrix A where m = rows and n = columns
[m,n] = size(A)

% You could also store it this way
dim_A = size(A)

% Get the dimension of the vector v 
dim_v = size(v)

% Now let's index into the 2nd row 3rd column of matrix A
A_23 = A(2,3)

/*


A =

    1    2    3
    4    5    6
    7    8    9
   10   11   12

v =

   1
   2
   3

m =  4
n =  3
dim_A =

   4   3

dim_v =

   3   1

A_23 =  6

*/