NumPy : Beginner's Guide - Third Edition

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 ...