Time for action – plotting a polynomial function

To illustrate how plotting works, let’s display some polynomial graphs. We will use the NumPy polynomial function poly1d to create a polynomial.

1. Take the standard input values as polynomial coefficients. Use the NumPy poly1d function to create a polynomial.

   func = np.poly1d(np.array([1, 2, 3, 4]).astype(float))

2. Create the x values with the NumPy linspace function. Use the range -10 to 10 and create 30 even spaced values.

   x = np.linspace(-10, 10, 30)

3. Calculate the polynomial values using the polynomial that we created in the first step.

   y = func(x)

4. Call the plot function; this does not immediately display the graph.

   plt.plot(x, y)

5. Add a label to the x axis with xlabel function.

   plt.xlabel('x’)

6. Add a label to the y axis with ylabel function.

   plt.ylabel('y(x)’)

7. Call the show function to display the graph.

   plt.show()

Here is a plot with polynomial coefficients 1, 2, 3, and 4:

What just happened?

We displayed a graph of a polynomial on our screen. We added labels...