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An m n matrix is an rectangular array of elements with m rows and n columns :. Matrices. denotes the element in the i th row and j th column. Partitioning in submatrices. Matrices y vectores son fundamentales en el estudio formal de todas las ramas de la ingeniería.
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An m n matrix is an rectangular array of elements with m rows and n columns: Matrices denotes the element in the ith row and jth column
Matrices y vectores son fundamentales en el estudio formal de todas las ramas de la ingeniería • Instrumentación • Diseño de circuitos • Comunicaciones • Microelectrónica
Vectors A column vector is a matrix with n rows and 1 column A row vector is a matrix with 1 row and n columns
Classification of matrices Square: m=n
Symmetric: aji = aij
Upper Triangular: aij = 0 when j < i
Lower Triangular: aij = 0 when j >i
Diagonal: aij = 0 when j i
Identity: aii = 1 aij = 0 when j i
Scalar multiplication B = kA • Dimensions: • Example
Matrix multiplication C = AB Only possible if the number of columns of A is equal to the number of rows of B
Matrix multiplicationis a non-commutative operation (generally):
Identity: aii = 1 aij = 0 when j i
Vector products: (u,v are column vectors) • Dot product or inner product • Outer product:
Scalar product (of vectors) The product of a row vector a and a column vector b is a scalar a b = a1b1 + ... + anbn
Trace The trace of a nxn matrix A is given by:
Properties of Matrix Operations • A+B = B+A • A+(B+C) = (A+B)+C • A(BC) = (AB)C • A(B+C) = AB+AC • (B+C)A = BA+CA • a(B+C) = aB+aC Commutative law for addition Associative law for addition Associative for multiplication Left distributive law Right distributive law Distributive law for scalar multiplication
(a+b)C = aC+bC a(bC) = (ab)C a(BC) = (aB)C
Transpose B = AT • Dimensions: • Formula: • Example
Alternative notation used in some books B = AT B = A’ In this course we use the first one (B = AT )
Symmetric matrix: AT = A • Skew-symmetric matrix: AT = -A
Symmetric Skew-symmetric Unitarymatrix
Alternative notation used in some books for Matrix Complex Conjugate In this notes we use the bar
ComplexHermitian Example:
examples: Hermitian: Skew-Hermitian Unitary
Exercises : (a) Find A such as: (b) Find A such as: