Specify the sizes of the work vectors and create the run-time parameters required by this C MEX S-function
#define MDL_SET_WORK_WIDTHS void mdlSetWorkWidths(SimStruct *S)
The Simulink® engine calls this optional method to enable this S-function to set the sizes of state and work vectors that it needs to store global data and to create run-time parameters (see Run-Time Parameters). The engine invokes this method after it has determined the input port width, output port width, and sample times of the S-function. This allows the S-function to size the state and work vectors based on the number and sizes of inputs and outputs and/or the number of sample times. This method specifies the state and work vector sizes via the macros ssGetNumContStates, ssSetNumDiscStates, ssSetNumRWork, ssSetNumIWork, ssSetNumPWork, ssSetNumModes, and ssSetNumNonsampledZCs.
A C-MEX S-function needs to implement this method only if it does not know the sizes of all the work vectors it requires when the engine invokes the function's mdlInitializeSizes method. If this S-function implements mdlSetWorkWidths, it should initialize the sizes of any work vectors that it needs to DYNAMICALLY_SIZED in mdlInitializeSizes, even for those whose exact size it knows at that point. The S-function should then specify the actual size in mdlSetWorkWidths. This method is only valid for simulation, and must be enclosed in a #if defined(MATLAB_MEX_FILE) statement.