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How Does Repmat Work in MATLAB?

Published in MATLAB Functions 2 mins read

Repmat is a powerful function in MATLAB that allows you to replicate and tile matrices and arrays. It's like creating a mosaic by copying and pasting smaller pieces. Let's break down how it works:

Understanding Repmat's Syntax

The basic syntax for repmat is:

B = repmat(A, m, n)
  • A: The original matrix or array you want to replicate.
  • m: The number of times you want to repeat A vertically (downwards).
  • n: The number of times you want to repeat A horizontally (across).

Examples:

  • Example 1: Simple Repetition
A = [1 2; 3 4];
B = repmat(A, 2, 3);

This code creates a matrix B by repeating matrix A twice vertically and three times horizontally.

B =
     1     2     1     2     1     2
     3     4     3     4     3     4
     1     2     1     2     1     2
     3     4     3     4     3     4
  • Example 2: Tiling
A = [1 2; 3 4];
B = repmat(A, 2, 2);

This code creates a matrix B by tiling matrix A twice in both the vertical and horizontal directions.

B =
     1     2     1     2
     3     4     3     4
     1     2     1     2
     3     4     3     4

Practical Applications:

  • Creating Patterns: You can use repmat to generate repeating patterns or textures.
  • Image Processing: Repmat is useful for repeating image blocks to create larger images.
  • Signal Processing: Replicating signals can be helpful for analyzing and manipulating them.

Key Points:

  • Repmat operates on the entire matrix or array, not individual elements.
  • The output of repmat is a new matrix or array, leaving the original unchanged.
  • You can use repmat with multi-dimensional arrays as well.

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