The Matrix * What is a matrix? Traditional answer ** List of row-lists, list of column-lists *** List of row-lists, list of column-lists (Quizzes) ** The matrix revealed *** Rows, columns, and entries *** Dict-of-rows/dict-of-columns representations ** Our Python implementation *** Identity matrix *** Converting between representations *** Module matutil *** The Mat class **** Using Mat **** Assertions in Mat **** Testing Mat with doctests * Column space and row space * Transpose ** Transpose (and Quiz) * Matrices as vectors * Matrix-vector and vector-matrix multiplication in terms of linear combinations ** Matrix-vector multiplication in terms of linear combinations *** Matrix-vector multiplication in terms of linear combinations: Lights Out *** Solving a matrix-vector equation *** Solving a matrix-vector equation: Lights Out *** Solving a matrix-vector equation: 2 × 2 special case *** The solver module ** Vector-matrix multiplication in terms of linear combinations *** Vector-matrix multiplication in terms of linear combinations: JunkCo ** Solving a matrix-vector equation *** The solver module, and floating-point arithmetic *** Checking the output from solve(A, b) * Matrix-vector multiplication in terms of dot-products ** Applications of dot-product definition of matrix-vector multiplication ** Formulating a system of linear equations as a matrix-vector equation *** Matrix-vector equation for sensor node ** Triangular matrix ** Computing sparse matrix-vector product * Matrix-matrix multiplication ** Matrix-matrix multiplication: vector-matrix definition *** Matrix-matrix multiplication: vector-matrix interpretation ** Matrix-matrix multiplication: matrix-vector definition ** Matrix-matrix multiplication: Dot-product definition ** Matrix-matrix multiplication: transpose ** Matrix-matrix multiplication: Column vectors ** Matrix-matrix multiplication: Row vectors ** Algebraic properties of matrix-vector multiplication * Null space of a matrix ** Solution space of a matrix-vector equation ** Error-correcting codes *** Error-correcting codes: Block codes *** Error-correcting codes: Linear binary block codes *** Hamming Code * Matrices and their functions ** From matrix to function ** From function to matrix *** From function to matrix: horizontal scaling *** From function to matrix: rotation by 90 degrees *** From function to matrix: rotation by θ degrees *** From function to matrix: translation *** From function to matrix: identity function *** Diagonal matrices * Linear functions: Which functions can be expressed as a matrix-vector product? ** Which functions are linear? *** A linear function maps zero vector to zero vector *** Linear functions: Pushing linear combinations through the function ** From function to matrix, revisited (proof algorithm works) ** Linear functions and zero vectors: Kernel ** Kernel and one-to-one ** Linear functions that are onto? ** The image of a linear function is a vector space ** Linear functions that are onto? * Inner product / Outer product of matrices * Matrix-matrix multiplication and function composition ** Associativity of matrix-matrix multiplication * From function inverse to matrix inverse ** Matrix inverse ** Invertible matrices: why care? ** Product of invertible matrices is an invertible matrix ** Matrix inverse * %%% Local Variables: %%% mode: org %%% eval: (auto-fill-mode t) %%% eval: (flyspell-mode t) %%% End: