MATLAB: Simulink mask using workspace variables

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In a Simulink mask I have the command disp(sprintf('(%4.2fx-%4.2f)',abs([a b]))). "a" and "b" are defined in the workspace as 2.2 and 6.8, respectively. In the command line I have the correct output (2.20x- 6.80). However, in the Simulink I ge the "???" error message. Using the preview of the mask editor, I get the message "could not evaluate MaskDisplay commands of the block xxx: Undefined function or variable 'a'."
How to correctly use variables from the workspace in Masks?
PS: I'm using Matlab R2016b.

Best Answer

The mask has a separate workspace, so what you need to do is get the values from the base workspace before using them.
There is a function called evalin which will let you evaluate an expression from a separate workspace. In this case, we want to grab a and b from the BASE workspace (where you defined a and b) and stick them in the mask's workspace.
An example of code that works for the mask display callback:
myVal = evalin('base','abs([a b])');
fprintf('(%4.2fx-%4.2f)',myVal);
- Sebastian
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