Summary
Non-commutative
- multiply A by B vs multiply B to A
- pre-multiply vs post-multiply
unless they are diagonal matrices
Rules
zero product -> product of two nonzero matrices can be 0
Block multiplication
- spread the multiplication to columns/rows
- rows of first, cols of second
Concept
Matrix multiplication
Size of matrices for the product to be well defined
Multiplication of diagonal matrices is commutative
Power of square matrices
Application
Row vector and column vector
Using the rules of matrix multiplication
Finding a specific column using block multiplication
Extra
Octave
octave
# Matrix multiplication
A * A