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Numpy Beginner's Guide (Update)

Numpy Beginner's Guide (Update)

By : Ivan Idris
2 (1)
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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)
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14
C. NumPy Functions' References
15
Index

Time for action – twiddling bits

We will now cover three tricks—checking whether the signs of integers are different, checking whether a number is a power of 2, and calculating the modulus of a number that is a power of 2. We will show an operators-only notation and one using the corresponding NumPy functions:

  1. The first trick depends on the XOR or ^ operator. The XOR operator is also called the inequality operator; so, if the sign bit of the two operands is different, the XOR operation will lead to a negative number (see https://www.khanacademy.org/computing/computer-science/cryptography/ciphers/a/xor-bitwise-operation).

    The following truth table illustrates the XOR operator:

    Input 1

    Input 2

    XOR

    True

    True

    False

    False

    True

    True

    True

    False

    True

    False

    False

    False

    The ^ operator corresponds to the bitwise_xor() function, and the < operator corresponds to the less() function:

    x = np.arange(-9, 9)
    y = -x
    print("Sign different?", (x ^ y) < 0)
    print(&quot...

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