You can download the complete script used in this article for free. Here is a full working example combining matrix generation, plotting, and PDF export.

% FREE_SCRIPTS/xnxn_matrix_plot_pdf.m
% Author: Open Source MATLAB Community
% Purpose: Generate an xnxn matrix, plot it, and export to PDF.
clear; close all; clc;
% Step 1: Define matrix size
n = input('Enter matrix dimension n (e.g., 30): ');
if isempty(n), n = 30; end
% Step 2: Create a sample xnxn matrix (symmetric for better visualization)
xnxn_matrix = gallery('poisson', n);  % Free test matrix
% Step 3: Plot as heatmap
h_fig = figure('Position', [100 100 800 600]);
imagesc(xnxn_matrix);
colormap(parula);
colorbar;
title(sprintf('Heatmap of %dx%d Matrix', n, n));
xlabel(sprintf('Columns (n=%d)', n));
ylabel(sprintf('Rows (n=%d)', n));
% Step 4: Export to PDF for free
pdf_name = sprintf('xnxn_matrix_plot_n%d.pdf', n);
exportgraphics(h_fig, pdf_name, 'Resolution', 300);
disp(['PDF saved as: ' pdf_name]);

Many websites charge for simple MATLAB scripts. Remember:

For large numbers of plots, use the print or exportgraphics function.

% After creating your plot
figure;
imagesc(xnxn_matrix);
colorbar;
title('My Matrix Visualization');
% Save as PDF (vector graphics)
exportgraphics(gcf, 'matrix_plot.pdf', 'ContentType', 'vector');

Tip: exportgraphics (introduced in R2020a) is the modern, cleaner method. It crops white space automatically.

A standard $n \times n$ matrix usually requires visualization that represents intensity, distribution, or topology. Below are the three standard methods covered in most technical guides.