MATLAB: Do I need to specify the datatype when I assign a variable in Embedded MATLAB block in Simulink 6.3 (R14SP3)

Question

I am using an Embedded MATLAB block in Simulink 6.3 (R14SP3). I have defined an expression:

m = int16(1);
m = 10;

When I run the model Simulink returns the following error message:

 Class mismatch (int16 ~= double).  The class to the left is the class of the left-hand side of the assignment.

Answer 1

This is expected behavior for the Embedded MATLAB Function Block.

In Embedded MATLAB once a variable is initialized its size and type may not be changed. Since the default type for a scalar is double the code

m = int16(1);
m = 10;

will error out because 10 is of type double and m is of type int16.

You can recast values for variable assignment in two ways.

1) Explicitly recast the value with the appropriate typcast function:

m = int16(1);
m = int16(10);

2) Implicitly recast the value using the colon operator:

m = int16(1);
m(:) = 10;

For more information on variable initialization and assignment in Embedded MATLAB Function Blocks see the documentation section titled: "Embedded MATLAB Coding Style", or you can execute the following in an MATLAB R2008a command window:

web([docroot '/toolbox/eml/ug/brdqvz_.html#bq2l74g']);