2/4/2015 linear dependence, linear independence, basis, dimension, examples. ________________________________________________________________________________ 2/2/2015 vector subspace, linear combination, linear span of a subset of a vector space, examples ________________________________________________________________________________ 1/30/2015 Definition of a vector space (with the field of scalars being either the field of all real numbers or all complex numbers) ________________________________________________________________________________ 1/28/2015 Review the definitiion of determinant, properties of determinants, computing determants using row/column operations. ________________________________________________________________________________ January 26, 2015 1. Special cases when the inverse of a square matrix A can be computed easily: (a) A is 2-by-2 (ther is a simple formula) (b) A is orthogonal (then the transpose of A is the inverse of A) (b') A is unitary (then the transpose conjugate of A is the inverse of A) (c) A=I+N, N^n=0, then I-N+N^2+...+(-1)^{n-1} N^{n-1} is the inverse of A 2. sign of permutations; definition of determinant as a sum of n! terms index by permutations, each term of which is a product of n entries of the nxn matrix multiplied by the sign of the permutation. ________________________________________________________________________________ 1/23/2015 Inverse of square matrices: definition and how to compute it using row operations criterion for a matrix to be invertible: procedurally (using row operations) and conceptually (rank = rank of augmented matrix) ________________________________________________________________________________ 1/21/2015 Rank of matrices, row rank = column rank, meaning of rank for system of linear equations ________________________________________________________________________________ 1/16/2015 Systems of linear equations, represented using matrix multliplication, Gaussian/row operations illustrated with an example, how to write down the independent solutions once one gets to the row-reduced echelon form ________________________________________________________________________________ 1/14/2015 definition of matrix multiplication, structural way of looking at the matrix multiplication: by columns and by rows