How to Create a Diagonal Matrix in MATLAB?

You can create a diagonal matrix in MATLAB using the diag function. This function takes a vector as input and creates a square matrix with the elements of the vector along the main diagonal.

Using the diag Function

Here's a simple example:

% Create a vector
v = [1 2 3 4];

% Create a diagonal matrix using the vector
D = diag(v);

% Display the diagonal matrix
disp(D);

This code will output the following diagonal matrix:

     1     0     0     0
     0     2     0     0
     0     0     3     0
     0     0     0     4

Creating Diagonal Matrices with Specific Values

You can also use the diag function to create diagonal matrices with specific values:

• Creating a matrix with a single value on the diagonal:

% Create a diagonal matrix with 5 on the diagonal
D = diag(5 * ones(1, 4));

% Display the diagonal matrix
disp(D);

This code will output a 4x4 matrix with 5 on the diagonal.

• Creating a matrix with a sequence of values on the diagonal:

% Create a diagonal matrix with a sequence of numbers
D = diag(1:5);

% Display the diagonal matrix
disp(D);

This code will output a 5x5 matrix with the numbers 1 to 5 on the diagonal.

Practical Insights

• The diag function is a versatile tool for creating diagonal matrices with various values and dimensions.
• You can use it to create identity matrices by passing a vector of ones to the function.
• Diagonal matrices are essential in linear algebra, and understanding how to create them is crucial for various applications.