What is difference between stem and plot in MATLAB?

In MATLAB, both the plot and stem functions are used to visualize data curves, but they represent data in fundamentally different formats:

• plot function: Displays continuous data values by connecting data points with straight line segments. Think of drawing the graph of y = sin(x) smoothly with a pencil without lifting it from the paper.
• stem function: Displays discrete data values by drawing vertical stems extending from the baseline (x-axis) to each data point with a marker at the top. Think of plotting y = sin(x) for specific angles (such as 0°, 15°, 30°, 45°, 60°, and 90°) and drawing individual vertical lines from the x-axis to each point.

MATLAB Code Example: Continuous vs. Discrete Visualization

Run the following MATLAB code to compare plot and stem side-by-side using subplots:

clc;
clear all;
close all;
% Generate 50 points linearly spaced between -pi and pi x = linspace(-pi, pi, 50);
y = sin(x);
% Subplot 1: Continuous representation using 
plot() sub
plot(1, 2, 1);
plot(x, y, 'b-', 'LineWidth', 1.5);
xticks([-pi 0 pi]);
xticklabels({'-pi', '0', 'pi'});
title('Continuous Plot: 
plot(x, y)');
xlabel('x (radians)');
ylabel('sin(x)');
grid on;
% Subplot 2: Discrete representation using stem() sub
plot(1, 2, 2);
stem(x, y, 'r', 'LineWidth', 1.2, 'MarkerFaceColor', 'r');
xticks([-pi 0 pi]);
xticklabels({'-pi', '0', 'pi'});
title('Discrete Stem Plot: stem(x, y)');
xlabel('x (radians)');
ylabel('sin(x)');
grid on;

Code Explanation

• linspace(-pi, pi, 50) creates a vector of 50 evenly spaced points from -π to π.
• subplot(1, 2, 1) and subplot(1, 2, 2) divide the figure window into two side-by-side panels.
• xticks and xticklabels format the x-axis tick marks using LaTeX notation (-π, 0, π).
• grid on adds a background grid for better visual clarity.

Conclusion: The plot panel presents a smooth, continuous waveform, whereas the stem panel highlights individual discrete sample points rooted at the baseline.