State space model discritization inside an embedded matlab function

Hi,

I am using a state space model that is linearized for a non-linear model and the equilibrium points are not specific but are determined from other (continuously changing) dynamics of the model. Hence, I am trying to form a state space model and discretize it within embedded matlab function using 'ss' and 'c2d' functions. But, I am notified with following list of errors -

"Simulink does not have enough information to determine output sizes for this block. If you think the errors below are inaccurate, try specifying types for the block inputs and/or sizes for the block outputs.

Undefined function or variable 'A_p_d'. Function 'Subsystem/MATLAB Function' (#196.4343.4348), line 125, column 9: "A_p_d" Launch diagnostic report.

Undefined function or variable 'C_p_d'. Function 'Subsystem/MATLAB Function' (#196.4390.4395), line 127, column 5: "C_p_d" Launch diagnostic report.

Errors occurred during parsing of MATLAB function 'linear_model_check/Subsystem/MATLAB Function'

Simulink cannot determine sizes and/or types of the outputs for block 'linear_model_check/Subsystem/MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

Simulink cannot determine sizes and/or types of the outputs for block 'linear_model_check/Subsystem/MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs."

Here A_p_d and C_p_d are the matrices I tried to determine after discritizing the continuous state space matrix.

I am using simulink 2018a. Is there a way to solve this problem? Any work around will also be appreciated where I can discretize the state space model in realtime (online).

Thank you!