From the error message you showed, it looks like the MATLAB function you entered into the Interpreted MATLAB Function Block is not being recognised. It seems like you've used the function 'first_order' which isn't a documented MATLAB function. More information what is supported in the Interpreted MATLAB function block can be found here : Interpreted MATLAB Function
If you are trying to implement a first order hold, or an first order transfer function, the following blocks might help you better:
Hello, I want to ask. Can you help me to solve my problem. I want to simulate this equation into the simulink. So, i want to get the graph modelling based on my equation. From this equation, how i can i do to get the simulink graph?. Thank You.