4.11: More Matrix Functions — Read

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MATLAB has several functions for rearranging or extracting parts of a matrix.

Function	Meaning
reshape(A, m, n)	changes the dimensions of A without changing the total number of elements
fliplr(A)	Flips the matrix left to right
flipud(A)	Flips the matrix upside down
rot90(A)	Rotates the matrix 90 degrees counterclockwise
tril(A)	Returns the lower triangular part of A
triu(A)	Returns the upper triangular part of A

Example \(\PageIndex{1}\)

Rearranging a 2D array.

A = [1 2 3; 
	4 5 6; 
	7 8 9
    3 12 8];

arr_1 = fliplr(A)

arr_2 = flipud(A)

arr_3 = rot90(A)

arr_4 = tril(A)

arr_5 = triu(A)

arr_6 = reshape(A, 3, 4)

Solution

arr_1 =

    3    2    1
    6    5    4
    9    8    7
    8   12    3

arr_2 =

    3   12    8
    7    8    9
    4    5    6
    1    2    3

arr_3 =

    3    6    9    8
    2    5    8   12
    1    4    7    3

arr_4 =

    1    0    0
    4    5    0
    7    8    9
    3   12    8

arr_5 =

   1   2   3
   0   5   6
   0   0   9
   0   0   0

arr_6 =

    1    3    8    6
    4    2   12    9
    7    5    3    8

Caution

When using the reshape function, the new shape must contain the same total number of elements as the original array. Also remember that MATLAB fills the reshaped array column by column. This may not always match what you expect if you are thinking row by row.

This page titled 4.11: More Matrix Functions was last modified on Tue, 30 Jun 2026 02:11:57 GMT and is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Zara Noroozi.

Contents

Text

Example \(\PageIndex{1}\)

Caution