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authorAnoop Jacob Thomas2010-10-12 14:30:53 +0530
committerAnoop Jacob Thomas2010-10-12 14:30:53 +0530
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+#+LaTeX_CLASS: beamer
+#+LaTeX_CLASS_OPTIONS: [presentation]
+#+BEAMER_FRAME_LEVEL: 1
+
+#+BEAMER_HEADER_EXTRA: \usetheme{Warsaw}\usecolortheme{default}\useoutertheme{infolines}\setbeamercovered{transparent}
+#+COLUMNS: %45ITEM %10BEAMER_env(Env) %10BEAMER_envargs(Env Args) %4BEAMER_col(Col) %8BEAMER_extra(Extra)
+#+PROPERTY: BEAMER_col_ALL 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 :ETC
+
+#+LaTeX_CLASS: beamer
+#+LaTeX_CLASS_OPTIONS: [presentation]
+
+#+LaTeX_HEADER: \usepackage[english]{babel} \usepackage{ae,aecompl}
+#+LaTeX_HEADER: \usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet}
+
+#+LaTeX_HEADER: \usepackage{listings}
+
+#+LaTeX_HEADER:\lstset{language=Python, basicstyle=\ttfamily\bfseries,
+#+LaTeX_HEADER: commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen},
+#+LaTeX_HEADER: showstringspaces=false, keywordstyle=\color{blue}\bfseries}
+
+#+TITLE: Matrices
+#+AUTHOR: FOSSEE
+#+EMAIL:
+#+DATE:
+
+#+DESCRIPTION:
+#+KEYWORDS:
+#+LANGUAGE: en
+#+OPTIONS: H:3 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t
+#+OPTIONS: TeX:t LaTeX:nil skip:nil d:nil todo:nil pri:nil tags:not-in-toc
+
+* Outline
+ - Creating Matrices
+ - using direct data
+ - converting a list
+ - Matrix operations
+ - Inverse of matrix
+ - Determinant of matrix
+ - Eigen values and Eigen vectors of matrices
+ - Norm of matrix
+ - Singular Value Decomposition of matrices
+
+* Creating a matrix
+ - Creating a matrix using direct data
+ : In []: m1 = matrix([1, 2, 3, 4])
+ - Creating a matrix using lists
+ : In []: l1 = [[1,2,3,4],[5,6,7,8]]
+ : In []: m2 = matrix(l1)
+ - A matrix is basically an array
+ : In []: m3 = array([[5,6,7,8],[9,10,11,12]])
+
+* Matrix operations
+ - Element-wise addition (both matrix should be of order ~mXn~)
+ : In []: m3 + m2
+ - Element-wise subtraction (both matrix should be of order ~mXn~)
+ : In []: m3 - m2
+* Matrix Multiplication
+ - Matrix Multiplication
+ : In []: m3 * m2
+ : Out []: ValueError: objects are not aligned
+ - Element-wise multiplication using ~multiply()~
+ : multiply(m3, m2)
+
+* Matrix Multiplication (cont'd)
+ - Create two compatible matrices of order ~nXm~ and ~mXr~
+ : In []: m1.shape
+ - matrix m1 is of order ~1 X 4~
+ - Creating another matrix of order ~4 X 2~
+ : In []: m4 = matrix([[1,2],[3,4],[5,6],[7,8]])
+ - Matrix multiplication
+ : In []: m1 * m4
+* Recall from ~array~
+ - The functions
+ - ~identity(n)~ -
+ creates an identity matrix of order ~nXn~
+ - ~zeros((m,n))~ -
+ creates a matrix of order ~mXn~ with 0's
+ - ~zeros_like(A)~ -
+ creates a matrix with 0's similar to the shape of matrix ~A~
+ - ~ones((m,n))~
+ creates a matrix of order ~mXn~ with 1's
+ - ~ones_like(A)~
+ creates a matrix with 1's similar to the shape of matrix ~A~
+ Can also be used with matrices
+
+* More matrix operations
+ Transpose of a matrix
+ : In []: m4.T
+* Exercise 1 : Frobenius norm \& inverse
+ Find out the Frobenius norm of inverse of a ~4 X 4~ matrix.
+ :
+ The matrix is
+ : m5 = matrix(arange(1,17).reshape(4,4))
+ - Inverse of A,
+ -
+ #+begin_latex
+ $A^{-1} = inv(A)$
+ #+end_latex
+ - Frobenius norm is defined as,
+ -
+ #+begin_latex
+ $||A||_F = [\sum_{i,j} abs(a_{i,j})^2]^{1/2}$
+ #+end_latex
+
+* Exercise 2: Infinity norm
+ Find the infinity norm of the matrix ~im5~
+ :
+ - Infinity norm is defined as,
+ #+begin_latex
+ $max([\sum_{i} abs(a_{i})^2])$
+ #+end_latex
+* ~norm()~ method
+ - Frobenius norm
+ : In []: norm(im5)
+ - Infinity norm
+ : In []: norm(im5, ord=inf)
+* Determinant
+ Find out the determinant of the matrix m5
+ :
+ - determinant can be found out using
+ - ~det(A)~ - returns the determinant of matrix ~A~
+* eigen values \& eigen vectors
+ Find out the eigen values and eigen vectors of the matrix ~m5~.
+ :
+ - eigen values and vectors can be found out using
+ : In []: eig(m5)
+ returns a tuple of /eigen values/ and /eigen vectors/
+ - /eigen values/ in tuple
+ - ~In []: eig(m5)[0]~
+ - /eigen vectors/ in tuple
+ - ~In []: eig(m5)[1]~
+ - Computing /eigen values/ using ~eigvals()~
+ : In []: eigvals(m5)
+* Singular Value Decomposition (~svd~)
+ #+begin_latex
+ $M = U \Sigma V^*$
+ #+end_latex
+ - U, an ~mXm~ unitary matrix over K.
+ -
+ #+begin_latex
+ $\Sigma$
+ #+end_latex
+ , an ~mXn~ diagonal matrix with non-negative real numbers on diagonal.
+ -
+ #+begin_latex
+ $V^*$
+ #+end_latex
+ , an ~nXn~ unitary matrix over K, denotes the conjugate transpose of V.
+ - SVD of matrix ~m5~ can be found out as,
+ : In []: svd(m5)
+* Summary
+ - Matrices
+ - creating matrices
+ - Matrix operations
+ - Inverse (~inv()~)
+ - Determinant (~det()~)
+ - Norm (~norm()~)
+ - Eigen values \& vectors (~eig(), eigvals()~)
+ - Singular Value Decomposition (~svd()~)
+
+* Thank you!
+#+begin_latex
+ \begin{block}{}
+ \begin{center}
+ This spoken tutorial has been produced by the
+ \textcolor{blue}{FOSSEE} team, which is funded by the
+ \end{center}
+ \begin{center}
+ \textcolor{blue}{National Mission on Education through \\
+ Information \& Communication Technology \\
+ MHRD, Govt. of India}.
+ \end{center}
+ \end{block}
+#+end_latex
+
+