Plotting Inequalities in Matplotlib

What will you learn?

Discover how to visually represent inequalities by plotting them in Python using Matplotlib. This tutorial will equip you with the skills to graphically showcase solutions to systems of inequalities.

Introduction to the Problem and Solution

When dealing with inequalities in Matplotlib, we can convert them into equations and then highlight the region that meets the criteria. This method enables us to demonstrate the solutions of multiple inequalities simultaneously through visual aids. By employing various plotting techniques and functions, we can effectively visualize these complex mathematical concepts.


import numpy as np
import matplotlib.pyplot as plt

# Define the inequality as an equation (e.g., y > 2x + 1)
# Create x values for plotting
x = np.linspace(-10, 10, 400)

# Define the inequality function (e.g., y > 2x + 1)
y1 = 2*x + 1

# Plot the inequality function
plt.plot(x, y1, label='y > 2x + 1')
plt.fill_between(x, y1, max(y1), color='skyblue', alpha=0.5)

# Customize plot labels and legend 
plt.title('Plotting Inequality: y > 2x + 1')

# Show plot

# Credit:

# Copyright PHD


To plot an inequality like ‘y > mx + c’ on a graph: – Generate x values using np.linspace() for points along the x-axis. – Calculate corresponding y values based on x to define the inequality function. – Visualize the line using plot() and shade the satisfying region with fill_between(). – Enhance clarity by adding labels (xlabel(), ylabel()) and a legend (legend()). – Display your plot with show().

    How do I change the inequality being plotted?

    You can modify the equation within your code that defines your function.

    Can I plot multiple inequalities on one graph?

    Yes! Define multiple functions and shade their respective regions on a single plot.

    What if my inequality is not linear?

    For non-linear inequalities, consider advanced techniques or transformations before plotting.

    Is it possible to customize colors or styles of my plots?

    Matplotlib offers extensive options for customizing colors, markers, line styles, etc.

    How do I add gridlines or annotations to my plot?

    Include gridlines using grid(True) and annotate points with text using annotate() in Matplotlib.


    In conclusion, you have acquired the ability to visually represent complex systems of inequalities through plotting in Python’s Matplotlib library. This visualization technique provides a clear graphical insight into intricate mathematical concepts. For further exploration of advanced plotting features or deeper understanding of mathematical aspects behind these visualizations, explore resources at

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