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Numpy Beginner's Guide (Update)

You're reading from   Numpy Beginner's Guide (Update) Build efficient, high-speed programs using the high-performance NumPy mathematical library

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Product type Paperback
Published in Jun 2015
Publisher
ISBN-13 9781785281969
Length 348 pages
Edition 1st 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 (16) Chapters Close

Preface 1. NumPy Quick Start FREE CHAPTER 2. Beginning with NumPy Fundamentals 3. Getting Familiar with Commonly Used Functions 4. Convenience Functions for Your Convenience 5. Working with Matrices and ufuncs 6. Moving Further with NumPy Modules 7. Peeking into Special Routines 8. Assuring Quality with Testing 9. Plotting with matplotlib 10. When NumPy Is Not Enough – SciPy and Beyond 11. Playing with Pygame A. Pop Quiz Answers B. Additional Online Resources C. NumPy Functions' References
Index

Time for action – drawing sawtooth and triangle waves

We will initialize t just like in the previous section. Again, k = 99 should be sufficient. In order to draw sawtooth and triangle waves, follow these steps:

  1. Set initial values for the function to zero:
    t = np.linspace(-np.pi, np.pi, 201)
    k = np.arange(1, 99)
    f = np.zeros_like(t)
  2. Compute the function values with the sin() and sum() functions:
    for i, ti in enumerate(t):
       f[i] = np.sum(np.sin(2 * np.pi * k * ti)/k)
    
    f = (-2 / np.pi) * f
  3. It's easy to plot the sawtooth and triangle waves since the value of the triangle wave should be equal to the absolute value of the sawtooth wave. Plot the waves as shown in the following:
    plt.plot(t, f, lw=1.0, label='Sawtooth')
    plt.plot(t, np.abs(f), '--', lw=2.0, label='Triangle')
    plt.title('Triangle and sawtooth waves')
    plt.grid()
    plt.legend(loc='best')
    plt.show()

    In the following figure, the triangle wave is the one with the dashed line:

    Time for action – drawing sawtooth and triangle waves

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