MATLAB - Data Types


Advertisements


MATLAB does not require any type declaration or dimension statements. Whenever MATLAB encounters a new variable name, it creates the variable and allocates appropriate memory space.

If the variable already exists, then MATLAB replaces the original content with new content and allocates new storage space, where necessary.

For example,

Total = 42

The above statement creates a 1-by-1 matrix named 'Total' and stores the value 42 in it.

Data Types Available in MATLAB

MATLAB provides 15 fundamental data types. Every data type stores data that is in the form of a matrix or array. The size of this matrix or array is a minimum of 0-by-0 and this can grow up to a matrix or array of any size.

The following table shows the most commonly used data types in MATLAB −

Data Type Description
int8 8-bit signed integer
uint8 8-bit unsigned integer
int16 16-bit signed integer
uint16 16-bit unsigned integer
int32 32-bit signed integer
uint32 32-bit unsigned integer
int64 64-bit signed integer
uint64 64-bit unsigned integer
single single precision numerical data
double double precision numerical data
logical logical values of 1 or 0, represent true and false respectively
char character data (strings are stored as vector of characters)
cell array array of indexed cells, each capable of storing an array of a different dimension and data type
structure C-like structures, each structure having named fields capable of storing an array of a different dimension and data type
function handle pointer to a function
user classes objects constructed from a user-defined class
java classes objects constructed from a Java class

Example

Create a script file with the following code −

str = 'Hello World!'
n = 2345
d = double(n)
un = uint32(789.50)
rn = 5678.92347
c = int32(rn)

When the above code is compiled and executed, it produces the following result −

str = Hello World!
n =  2345
d =  2345
un = 790
rn = 5678.9
c =  5679

Data Type Conversion

MATLAB provides various functions for converting, a value from one data type to another. The following table shows the data type conversion functions −

Function Purpose
char Convert to character array (string)
int2str Convert integer data to string
mat2str Convert matrix to string
num2str Convert number to string
str2double Convert string to double-precision value
str2num Convert string to number
native2unicode Convert numeric bytes to Unicode characters
unicode2native Convert Unicode characters to numeric bytes
base2dec Convert base N number string to decimal number
bin2dec Convert binary number string to decimal number
dec2base Convert decimal to base N number in string
dec2bin Convert decimal to binary number in string
dec2hex Convert decimal to hexadecimal number in string
hex2dec Convert hexadecimal number string to decimal number
hex2num Convert hexadecimal number string to double-precision number
num2hex Convert singles and doubles to IEEE hexadecimal strings
cell2mat Convert cell array to numeric array
cell2struct Convert cell array to structure array
cellstr Create cell array of strings from character array
mat2cell Convert array to cell array with potentially different sized cells
num2cell Convert array to cell array with consistently sized cells
struct2cell Convert structure to cell array

Determination of Data Types

MATLAB provides various functions for identifying data type of a variable.

Following table provides the functions for determining the data type of a variable −

Function Purpose
is Detect state
isa Determine if input is object of specified class
iscell Determine whether input is cell array
iscellstr Determine whether input is cell array of strings
ischar Determine whether item is character array
isfield Determine whether input is structure array field
isfloat Determine if input is floating-point array
ishghandle True for Handle Graphics object handles
isinteger Determine if input is integer array
isjava Determine if input is Java object
islogical Determine if input is logical array
isnumeric Determine if input is numeric array
isobject Determine if input is MATLAB object
isreal Check if input is real array
isscalar Determine whether input is scalar
isstr Determine whether input is character array
isstruct Determine whether input is structure array
isvector Determine whether input is vector
class Determine class of object
validateattributes Check validity of array
whos List variables in workspace, with sizes and types

Example

Create a script file with the following code −

x = 3
isinteger(x)
isfloat(x)
isvector(x)
isscalar(x)
isnumeric(x)
 
x = 23.54
isinteger(x)
isfloat(x)
isvector(x)
isscalar(x)
isnumeric(x)
 
x = [1 2 3]
isinteger(x)
isfloat(x)
isvector(x)
isscalar(x)
 
x = 'Hello'
isinteger(x)
isfloat(x)
isvector(x)
isscalar(x)
isnumeric(x)

When you run the file, it produces the following result −

x = 3
ans = 0
ans = 1
ans = 1
ans = 1
ans = 1
x = 1177/50
ans = 0
ans = 1
ans = 1
ans = 1
ans = 1
x =

          1          2          3

ans = 0
ans = 1
ans = 1
ans = 0
x = Hello
ans = 0
ans = 0
ans = 1
ans = 0
ans = 0


Advertisements