Time for action – plotting a polynomial and its derivatives

Let's plot a polynomial and its first-order derivative using the deriv() function with m as 1. We already did the first part in the previous Time for action section. We want two different line styles to discern what is what.

  1. Create and differentiate the polynomial:
    func = np.poly1d(np.array([1, 2, 3, 4]).astype(float))
func1 = func.deriv(m=1)
x = np.linspace(-10, 10, 30)
y = func(x)
y1 = func1(x)
  2. Plot the polynomial and its derivative in two styles: red circles and green dashes. You cannot see the colors in a print copy of this book, so you will have to try the code out for yourself:
    plt.plot(x, y, 'ro', x, y1, 'g--')
plt.xlabel('x')
plt.ylabel('y')
plt.show()

    The graph with polynomial coefficients 1, 2, 3, and 4 is as follows:

    Time for action – plotting a polynomial and its derivatives

What just happened?

We plotted a polynomial and its derivative using two different line styles and one call of the plot() function (see polyplot2.py):

import numpy as np
import matplotlib.pyplot as plt

func = np.poly1d(np.array([1, 2, 3, 4]).astype(float))
func1 = func.deriv(m=1)
x = np.linspace(-10, 10, 30)
y = func(x)
y1 = func1(x)

plt.plot(x, y, 'ro', x, y1, 'g--')
plt.xlabel('x')
plt.ylabel('y')
plt.show()
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