Plotting Mathematical Functions With Matplotlib

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The following source code shows how to plot two mathematical functions (one linear and one quadratic) using the Matplotlib library, save the result to a PNG image, and display it on the screen. The functions are:

  • Quadratic: \(f_1(x) = 2x^2 + 5x - 2\)

  • Linear: \(f_2(x) = 4x + 1\)

This is the resulting image:

/images/plotting-mathematical-functions-with-matplotlib/linear-and-quadratic-plot.png

And the code:

import matplotlib.pyplot as plt
# Quadratic function.
def f1(x):
    return 2*(x**2) + 5*x - 2
# Linear function.
def f2(x):
    return 4*x + 1
# The X values to be plotted.
x = range(-10, 15)
# Plot both functions.
# The second argument calculates the Y value for each of
# the X values defined above.
plt.plot(x, [f1(i) for i in x])
plt.plot(x, [f2(i) for i in x])
# Configure the color of the axes.
plt.axhline(0, color="black")
plt.axvline(0, color="black")
# The range of values shown by each axis.
plt.xlim(-10, 10)
plt.ylim(-10, 10)
# Save the plot as a PNG image.
plt.savefig("output.png")
# Show the result.
plt.show()

The Matplotlib library required by this code can be installed via python -m pip install matplotlib.

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