Open In App

Variable Names in MATLAB

Last Updated : 22 Sep, 2021
Improve
Improve
Like Article
Like
Save
Share
Report

A variable is a named-memory location that stores different types of data which can be used to perform a specific set of operations. It can be thought of as a container that holds some value in memory. The Matlab workspace store all the variables being used during a session. This workspace not only deals with the creation of new variables but also supports the reusing of existing variables in the execution of the command. Each variable in the Matlab environment is treated as a matrix or an array of different data types. In Matlab, variables are assigned using the assignment ‘=’ operator. 

Note:

  • After the creation of a variable, we can use it later in our program.
  • There must have values assigned to variables before they are used.
  • If an expression returns a result without being assigned to any variable, the system implicitly assigns and stores the value to a special variable named ‘ans’. But ans variable is specific to the current workspace and the value of ans can change frequently, that is why the use of ans in a script or function is not recommended.

Example 1: 

Matlab




% MATLAB code for defining a and initializing 
% it with a value 10 using assignment operator '='
a = 10


Output:

a = 10

Example 2:

Matlab




% MATLAB code for calculates an expression
% and stores value 13 in variable b
b = sqrt(169)


Output:

b = 13

Example 3:

Matlab




% MATLAB code to stores the expression 
% in special variable 'ans'
sqrt(169)


Output:

ans = 13

Rules for creating a variable:

A variable name is the name of the memory location where we can store our values. Some of the rules for naming a variable are:

  • A variable name should start with a letter followed by digits, underscores, or letters.
  • Don’t use Matlab keywords as variable names.
  • Matlab is case sensitive, i.e., small letters and capital letters are treated differently. For example, variable names ‘PRICE’ and Price are different.
  • A variable name cannot contain letters more than name length max characters.
  • Special symbols anywhere in a variable name are syntactically invalid in Matlab.
  • Avoid naming variable names as provided by pre-defined Matlab’s variable names.
Examples of valid variable names: Examples of invalid variable names:
Principal 8a
F_Value 1_Digit
Digit_1 Roll_No!
a10 end
Roll_no if

Check whether a variable name is a Matlab keyword:

To check whether a variable name is a MATLAB keyword or not, MATLAB provides a built-in function iskeyword( ). This keyword determines whether the input is MATLAB keyword or not.

Syntax:

v = iskeyword(txt)
iskeyword

Example 1:

Matlab




% MATLAB code for check variable
% is keyword or not
Test=iskeyword('if'% this statement returns 
  
% logical True (1) as a result as 'if' is a keyword 
% in the Matlab otherwise returns false. 
  
iskeyword if  % this statement uses the Matlab 
% command format and results in ans=1.            


Test = logical
       1

ans = logical
      1

Example 2:

Matlab




% MATLAB code for print all keyword
iskeyword % returns a list of all Matlab keywords.


  Output:  

 Check whether the input is a valid variable name:

To check whether the input is a valid variable name isvarname( ) is used. This function determines if the input is a valid variable name. If it is a valid MATLAB variable name the isvarname function returns logical 1 (true). Otherwise, it returns logical 0 (false).

Syntax:

t = isvarname(s)

isvarname s

Example 1:

Matlab




% MATLAB code for isvarname
isvarname Number_1


Output:

ans = logical
    1

Example 2:

Matlab




% MATLAB code for isvarname()
Test= isvarname(Digit_1)


Output:

Test = logical
      1

Conflicts between variable and function name:

Matlab provides some predefined functions such as pi, ans, i, j, clock, date, eps which cannot be used as variable names as they can create confliction between variable name and functions name.  Usually, variable names take precedence over function names that result in unexpected results.

To check whether a variable name is already used with function:

Example:

Matlab




% MATLAB code for check if there is no
% existing variables or functions name. In case it exists, 
% remove the variable from the memory with the clear() function. 
exist varname 


Output:

ans=0

genvarname()

This function (generate variable name)  is used to construct a valid and unique variable name. It returns an array of strings or characters that can be used as a legal variable name. Argument str can be a string, a string array, a character array, or a cell array containing character vectors. All the returned elements are unique. 

Syntax:

varname = genvarname(str)

varname = genvarname(str, exclusions)

here genvarname(str, exclusions) returns a legal variable name that is different from any name listed in the exclusions input. The argument exclusions can be a string, a string array, a character array, a cell array of character vectors.

Example 1:

Matlab




% MATLAB code for gemvarname()
var_name = genvarname({'Pen', 'Pen', 'Pen', 'Pen'})


Output:

var_name = 1X4 cell
  'Pen_1'   'Pen_2'   'Pen_3'    'Pen_4'

Example 2:

Matlab




% MATLAB code for genvarname() with different parameters
a = ["Pen", "Eraser", "Pencil", "Box" ]
var_name=genvarname(a,"Box")


Output:

var_name= 1x4 string
"Pen"  "Eraser"   "Pencil"   "Box1"

 

 

 



Similar Reads

Clear variable from Memory in MATLAB
Clearing variables from memory, with the help of clearvars operation. The clearvars operation is used to clear the specified variables from memory or from the currently active workspace. Syntax:clearvars variables clearvars -except keepVariables Parameters: This function accepts a parameter. variables: These are the specified variables that are goi
1 min read
Set environment variable in MATLAB
Setting environment variables with the help of setenv() function. The setenv() function is used to set the specified value of an operating system environment variable. Here the environment variable "name" will be replaced with "value", where "name" and "value" is its parameters. Syntaxsetenv(name, value) Parameters: This function accepts two parame
1 min read
Get environment variable in MATLAB
In this article, we are going to discuss "Getting environment variable", which can be done using getenv() function. The getenv() function is used to get the operating system environment variable. Syntax:value = getenv(name) Parameters: This function accepts a parameter name parameter. name: This is the specified name for which environmental variabl
1 min read
Function With Variable Number of Input Arguments in MATLAB
MATLAB functions have the functionality that many other programming languages lack. A MATLAB function can take a variable number of input arguments, without the use of arrays or any additional functionality. The way to go about this in MATLAB is by using the varargin - which can be interpreted as VARiable ARGument INput. Now, the way to use varargi
2 min read
Set Variable Data Types in MATLAB
There are many cases when a user has to import data into MATLAB script from various files. These file types could be .txt, .xlsx, .csv, .dat, etc. types. Now, each file type has its own method of defining data types. However, for computation purposes, MATLAB requires the data to be of numeric type, rather than character. Thus, there is a requiremen
3 min read
How to Select Random Rows from a Matrix in MATLAB?
A matrix is an n x n array that stores integers, floating point numbers or alphanumeric data in MATLAB. Indexing a matrix is the same as indexing an array. Syntax:matrix_name(i,j)where, i is the row number, and J is the column number which is to be indexed. Example 1: C/C++ Code % MATLAB code for select % random matrix elements mat = magic(5); mat(
2 min read
MATLAB Annotation
Annotations in MATLAB is a way of adding explanation or notes to the plots. Annotations add more information to the plots. There are different syntax formations for adding annotations to a plot: annotation(lineType,x,y)annotation(lineType)annotation(shapeType,dim)annotation(shapeType)annotation(___,Name,Value) Let's discuss all the above functions
3 min read
Global Variables in MATLAB
Variables in programming are generally storage spaces to store a certain type of data. There are many types of variables, but two commonly used types are local and Global variables. Generally, each MATLAB function has its own local variables. But sometimes for the sake of programming, we need to change the value of the local variable in another fun
4 min read
How to Calculate Harmonic Mean in MATLAB?
Harmonic mean is a type of mean, which is a measure of central tendencies of data, in statistics that gives large weightage to smaller data and small weightage to larger data. The Harmonic Mean in mathematical terms is nothing but the reciprocal of the mean of reciprocal values of all the data elements. Harmonic Mean in MATLAB:MATLAB provides a bui
2 min read
Copy Objects in MATLAB
In MATLAB, there are two kinds of objects - handles and values. The value objects are ordinary MATLAB objects which behave normally to copy operations. It means that when a value object is copied, the new copies of that object are completely independent of the original one i.e., if the original's value is changed, the copied object will not be chan
2 min read
Article Tags :