Determine if a variable-step solver is being used to solve the S-function
boolean_T ssIsVariableStepSolver(SimStruct *S)
The Boolean value true if the solver being used to solve S is a variable-step solver. Otherwise, returns false.
Use to determine if the simulation is being solved using a variable or fixed-step solver. This is useful when you are creating S-functions that have zero crossings and an inherited sample time.