Sign In Start Free Trial
Account

Add to playlist

Create a Playlist

Modal Close icon
You need to login to use this feature.
  • Book Overview & Buying Numpy Beginner's Guide (Update)
  • Table Of Contents Toc
  • Feedback & Rating feedback
Numpy Beginner's Guide (Update)

Numpy Beginner's Guide (Update)

By : Ivan Idris
2 (1)
close
close
Numpy Beginner's Guide (Update)

Numpy Beginner's Guide (Update)

2 (1)
By: Ivan Idris

Overview of this book

This book is for the scientists, engineers, programmers, or analysts looking for a high-quality, open source mathematical library. Knowledge of Python is assumed. Also, some affinity, or at least interest, in mathematics and statistics is required. However, I have provided brief explanations and pointers to learning resources.
Table of Contents (16 chapters)
close
close
14
C. NumPy Functions' References
15
Index

Time for action – inverting matrices

The inverse of a matrix A in linear algebra is the matrix A-1, which, when multiplied with the original matrix, is equal to the identity matrix I. This can be written as follows:

A A-1 = I

The inv() function in the numpy.linalg package can invert an example matrix with the following steps:

  1. Create the example matrix with the mat() function we used in the previous chapters:
    A = np.mat("0 1 2;1 0 3;4 -3 8")
    print("A\n", A)

    The A matrix appears as follows:

    A
    [[ 0  1  2]
     [ 1  0  3]
     [ 4 -3  8]]
    
  2. Invert the matrix with the inv() function:
    inverse = np.linalg.inv(A)
    print("inverse of A\n", inverse)

    The inverse matrix appears as follows:

    inverse of A
    [[-4.5  7.  -1.5]
     [-2.   4.  -1. ]
     [ 1.5 -2.   0.5]]
    

    Tip

    If the matrix is singular, or not square, a LinAlgError is raised. If you want, you can check the result manually with a pen and paper. This is left as an exercise for the reader.

  3. Check the result by multiplying the original matrix...

Unlock full access

Continue reading for free

A Packt free trial gives you instant online access to our library of over 7000 practical eBooks and videos, constantly updated with the latest in tech

Create a Note

Modal Close icon
You need to login to use this feature.
notes
bookmark search playlist font-size

Change the font size

margin-width

Change margin width

day-mode

Change background colour

Close icon Search
Country selected

Close icon Your notes and bookmarks

Delete Bookmark

Modal Close icon
Are you sure you want to delete it?
Cancel
Yes, Delete

Delete Note

Modal Close icon
Are you sure you want to delete it?
Cancel
Yes, Delete

Edit Note

Modal Close icon
Write a note (max 255 characters)
Cancel
Update Note

Confirmation

Modal Close icon
claim successful

Buy this book with your credits?

Modal Close icon
Are you sure you want to buy this book with one of your credits?
Close
YES, BUY