ParX

Conditional Evaluation

A simple example of a model using a conditional assignment:


                                        
conditional.parx

                                    
                                        
All combinations of the variables x
                                            and y where the residual zero = 0
                                            are part of the model behavior.
                                            When choosing x as the independent variable, we have modeled the formula:

                                    
                                        
y = c1 * abs(x) + c0

                                        
Or expressed as a ParX model:

                                    
                                        

                                        
absolute.parx

                                    
                                        

                                    
                                        
A more complex example containing nested conditionals is given by this piece-wise linear model:

                                    
                                        

                                        
piecewise.parx

                                    
                                        
Because the three segments are split on the basis of a condition on x
                                            it is not possible to determine the distance to the data points in the x-direction.
                                            The discontinuities at the segment boundaries may preclude the existence of the nearest point on the model curve.
                                            Therefore the x variable must be set to fixed in the data pane.
                                        

                                    
                                        

                                            Always try to make your conditional models continuous,
                                            both the equation itself and its first-order derivatives with regard to all the variables.