MATLAB: It is necessary to declare the data type each time I change the value

Question

Hello everybody,

I want to declare x as an int8.

For example

x = int8(9);

But if I change to

x= 2;

Then, it changes to double, so I have to do

x = int8(2);

Is there any way to declare x as an int8 in all my script and when I code

    x=2

It remains as a int8?

Answer 1

MATLAB does not give you the ability to set a variable name as automatically a specific data type. (Unlike old Fortran, where I could tell it that all variables that begin with the letters i through n were of integer type automatically.)

So even though you initially assign

x = int8(9);

then when you do this:

x = 2;

MATLAB sees that 2 is a double precision value, and the assignment "x=" overrides the current datatype of x. So x is now a double.

You have two choices that I can think of.

x = int8(2);

must work of course, since that just overwrites x. But you can also use this form:

x(:) = 2;

x was initially a scalar, of class int8. But the assignment as x(:)= does not overwrite the variable type. It uses the current type of x. As a test try this:

x = int8(9);
whos x
Name      Size            Bytes  Class    Attributes
x         1x1                 1  int8               
x(:) = 2;
whos x
Name      Size            Bytes  Class    Attributes
x         1x1                 1  int8               
x
x =
  int8
   2

So x remains an int8, without needing to recast x as int8.