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Revision as of 05:32, 26 November 2010 by Admin (talk | contribs) (→‎Functions)

Matrices

Basics

See Introduction to Matlab

Special matrices/vectors

Name (matrix type) Matlab syntax Result
Ones
>> ones(3,2);
$ \left[ \begin{array}{cc} 1 & 1 \\ 1 & 1 \\ 1 & 1 \end{array} \right] $
Zeros
>> zeros(3,1);
$ \left[ \begin{array}{cc} 0 \\ 0 \\ 0 \end{array} \right] $
Eye (identity)
>> eye(3);
$ \left[ \begin{array}{ccc} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array} \right] $
Rand (random numbers)
>> rand(3,2);
$ \left[ \begin{array}{cc} 0.21955 & 0.27560\\ 0.42385 & 0.62212\\ 0.53343 & 0.69182 \end{array} \right] $
Meshgrid
>> [x,y] = meshgrid(1:4,1:4);
$ x = \left[ \begin{array}{cccc} 1& 2& 3& 4\\ 1& 2& 3& 4\\ 1& 2& 3& 4\\ 1& 2& 3& 4 \end{array} \right] $

$ y = \left[ \begin{array}{cccc} 1& 1& 1& 1\\ 2& 2& 2& 2\\ 3& 3& 3& 3\\ 4& 4& 4& 4 \end{array} \right] $

Magic (magic square matrix)

(The sum of each row and column is equal to the same value)

>> magic(4);
$ \left[ \begin{array}{cccc} 16& 2& 3& 13\\ 5& 11& 10& 8\\ 9& 7& 6& 12\\ 4& 14& 15& 1 \end{array} \right] $

Functions

linspace

logspace

Function name Matlab syntax/output
det Returns the determinant of a matrix:
>> A=magic(4)
A =

   16    2    3   13
    5   11   10    8
    9    7    6   12
    4   14   15    1

>> det(A)
ans = -1.4495e-12
find
flipud
fliplr
length
max
min
repmat This function creates a new matrix consisting of several copies of an existing matrix.
>> A = magic(3)
A =

   8   1   6
   3   5   7
   4   9   2

>> repmat(A,2,2)
ans =

   8   1   6   8   1   6
   3   5   7   3   5   7
   4   9   2   4   9   2
   8   1   6   8   1   6
   3   5   7   3   5   7
   4   9   2   4   9   2
size
sort

Operators

Input/output

Switches

Functions

Graphics

Examples

Fluid mechanics

Heat transfer

Optimization

Statistics

See also