Creating Double-Precision Data
Because the default numeric type for MATLAB is double, you can create a double with a simple
assignment statement:
x = 25.783;
The whos function shows that MATLAB has created a 1-by-1 array of type double for the value you
just stored in x:
whos x
Name
Size
Bytes Class
x
1x1
8 double
Use isfloat if you just want to verify that x is a floating-point number. This function returns logical
1 (true) if the input is a floating-point number, and logical 0 (false) otherwise:
isfloat(x)
ans =
logical
1
You can convert other numeric data, characters or strings, and logical data to double precision using
the MATLAB function, double. This example converts a signed integer to double-precision floating
point:
y = int64(-589324077574);
% Create a 64-bit integer
x = double(y)
% Convert to double
x =
-5.8932e+11
Creating Single-Precision Data
Because MATLAB stores numeric data as a double by default, you need to use the single
conversion function to create a single-precision number:
x = single(25.783);
The whos function returns the attributes of variable x in a structure. The bytes field of this structure
shows that when x is stored as a single, it requires just 4 bytes compared with the 8 bytes to store it
as a double:
xAttrib = whos('x');
xAttrib.bytes
ans =
4
You can convert other numeric data, characters or strings, and logical data to single precision using
the single function. This example converts a signed integer to single-precision floating point:
y = int64(-589324077574);
% Create a 64-bit integer
x = single(y)
% Convert to single
x =
Floating-Point Numbers
4-7