Special Matrices
From ControlTheoryPro.com

1 Special Matrices
There are special matrices available in MATLAB. These matrices are often useful for initializing, comparisons, etc. (Note that initializing large variable before a loop allows the loop to execute much faster. See MATLAB Code Optimization for more details.)
1.1 Identity matrix
To create an identity matrix (ones along the diagonal and zeroes elsewhere) use the MATLAB command eye
>> a = eye(3) a = 1 0 0 0 1 0 0 0 1 >> a = eye(3, 3) a = 1 0 0 0 1 0 0 0 1
1.2 Ones Matrix
To create a matrix of all ones use the MATLAB command ones
>> a = ones(2, 3) a = 1 1 1 1 1 1
1.3 Zero matrix
To create a matrix of zeros use the MATLAB command zeros
>> a = zeros(2, 3) a = 0 0 0 0 0 0