MATLAB: Change data type in matlab

matlab workspace simulink

Hey,

I'll present my question with an example.

I create parameter: x=1; now we have the possibility to see in workspace, among many others, the class of this parameter which automatically will be 'double'.

I have this parameter in a Simulink model, where I use it as an int8. Next I want to determine the byte size for this parameter x.

But the problem is that in Matlab workspace the data type of parameter x is double. I need to change the class from double to int8 (adapt it as in the Simulink model).

How can I do this considering that x=1 is in workspace as a parameter and I have another 2 variables: var_param_name=x (type char) and var_data_type=int8 (type char). I managed to obtain these 2 variables from workspace with find_system command.

Thanks! Diana

Best Answer

So you have a = 1 in you workspace which is a double. You also have b = 'int8' which is a char.

I think you can use the eval command which will execute a string command. So this means that you have to create your command as a string.

c = strcat(b,'(',int2str(a),')')

This will actually store into your workspace a 'c' string with the value:

c = 'int8(1)'

Now you can simply pass this string to the eval command.

So a = eval (c), and there it is:

a = 1, as an int8. :D

Good luck!

Anca Acreala

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MATLAB: How to access the variables in base workspace in GUI

This might work,

evalin('base','temp = who(''signal_*'',''base'');assignin(''caller'',''all_signals'',temp)');

Hope that helps,

Ilham

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

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.

Best Answer

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

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