MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guía de usuario descargar pdf (Pagina 121)

Examples of C MEX-File S-Function Blocks

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* Modes and zero crossings:

* If we have a variable step solver and this block has a continuous

* sample time, then

* o One mode element will be needed for each scalar output

* in order to specify which equation is valid (1), (2), or (3).

* o Two ZC elements will be needed for each scalar output

* in order to help the solver find the exact instants

* at which either of the two possible "equation switches."

* One will be for the switch from eq. (1) to (2);

* the other will be for eq. (2) to (3) and vise versa.

* otherwise

* o No modes and nonsampled zero crossings will be used.

ssSetNumModes(S, DYNAMICALLY_SIZED);

ssSetNumNonsampledZCs(S, DYNAMICALLY_SIZED);

* options

* o No mexFunctions and no problematic mxFunctions are called

* so the exception free code option safely gives faster simulations.

* o Scalar expansion of the inputs is desired. The option provides

* this without the need to write mdlSetOutputPortWidth and

* mdlSetInputPortWidth functions.

ssSetOptions(S, ( SS_OPTION_EXCEPTION_FREE_CODE |

SS_OPTION_ALLOW_INPUT_SCALAR_EXPANSION));

} /* end mdlInitializeSizes */

/* Function: mdlInitializeSampleTimes =========================================

* Abstract:

* Specify that the block is continuous.

static void mdlInitializeSampleTimes(SimStruct *S)

{

ssSetSampleTime(S, 0, INHERITED_SAMPLE_TIME);

ssSetOffsetTime(S, 0, 0);

}

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MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guía de usuario Pagina 121