Page 3: Matrix Multiplication

This page details the rules and properties of matrix multiplication, including scalar multiplication and matrix product operations.

Definition: Matrix multiplication requires the number of columns in the first matrix to equal the number of rows in the second matrix.

Example: Product of a row matrix by a column matrix:

[1 2 3] × [4]   [1×4 + 2×5 + 3×6]
         [5] =  
         [6]

Highlight: Matrix multiplication is not generally commutative (AB ≠ BA).

Page 5: Matrix Powers and Transpose

This page covers matrix powers and the concept of matrix transpose, including their properties and calculations.

Definition: The transpose of a matrix A (denoted as At) is obtained by switching rows and columns.

Vocabulary:

• Symmetric matrix: A matrix equal to its transpose
• Anti-symmetric matrix: A matrix equal to the negative of its transpose

Highlight: For diagonal matrices, calculating powers is simplified by raising diagonal elements to the corresponding power.

Page 6: Matrix Inverse

This section explains the concept of matrix inverse and methods for finding inverse matrices.

Definition: A square matrix A is invertible if there exists another matrix A⁻¹ such that AA⁻¹ = A⁻¹A = I (identity matrix).

Example: Finding the inverse of a 2x2 matrix through system solving.

Page 1: Introduction to Matrices

This page introduces fundamental matrix concepts and classifications. A matrix is defined as an arrangement of numbers in rows and columns, with specific dimensions denoted as nxm.

Definition: A matrix of dimension nxm consists of n rows and m columns arranged in a rectangular array.

Vocabulary:

• Rectangular matrix: Different number of rows and columns
• Square matrix: Equal number of rows and columns
• Triangular matrix: Contains zeros above or below the main diagonal

Example: A 2x3 matrix example is provided:

[2 3 4]
[5 6 7]

Highlight: The main diagonal elements (ai,i) sum is called the trace of a matrix.