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NumPy Beginner's Guide

You're reading from   NumPy Beginner's Guide An action packed guide using real world examples of the easy to use, high performance, free open source NumPy mathematical library.

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Product type Paperback
Published in Apr 2013
Publisher Packt
ISBN-13 9781782166085
Length 310 pages
Edition 2nd Edition
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Author (1):
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Ivan Idris Ivan Idris
Author Profile Icon Ivan Idris
Ivan Idris
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Table of Contents (19) Chapters Close

Numpy Beginner's Guide Second Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
1. NumPy Quick Start FREE CHAPTER 2. Beginning with NumPy Fundamentals 3. Get in Terms with Commonly Used Functions 4. Convenience Functions for Your Convenience 5. Working with Matrices and ufuncs 6. Move Further with NumPy Modules 7. Peeking into Special Routines 8. Assure Quality with Testing 9. Plotting with Matplotlib 10. When NumPy is Not Enough – SciPy and Beyond 11. Playing with Pygame Pop Quiz Answers Index

Time for action – determining eigenvalues and eigenvectors


Let's calculate the eigenvalues of a matrix. Perform the following steps to do so:

  1. Create a matrix as follows:

    A = np.mat("3 -2;1 0")
    print "A\n", A

    The matrix we created looks like the following:

    A
    [[ 3 -2]
     [ 1  0]]
    
  2. Calculate eigenvalues by calling the eig function.

    print "Eigenvalues", np.linalg.eigvals(A)

    The eigenvalues of the matrix are as follows:

    Eigenvalues [ 2.  1.]
    
  3. Determine eigenvalues and eigenvectors with the eig function. This function returns a tuple, where the first element contains eigenvalues and the second element contains corresponding Eigenvectors, arranged column-wise.

    eigenvalues, eigenvectors = np.linalg.eig(A)
    print "First tuple of eig", eigenvalues
    print "Second tuple of eig\n", eigenvectors

    The eigenvalues and eigenvectors will be shown as follows:

    First tuple of eig [ 2.  1.]
    Second tuple of eig
    [[ 0.89442719  0.70710678]
     [ 0.4472136   0.70710678]]
    
  4. Check the result with the dot function by calculating the right...

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