Model of a smooth thooth signal.
The output ( y ) remains at its initial value yin
until the enabling input ENup remains false.
Then the signal changes smoothly. After the smoth start the signal grows up linearly with a slope m.
When the output signal is close to the final value yfin, it is reached smoothly.
The signal returns at its initial value in a specular way, when the input ENup becomes true.
The parameter alfa (that has to be coprises between 0 and 1), indicates the portion of the rising
time occupied by the smooth junction.
The rising is delayed by wait_s seconds, while the falling is delayed by wait_d seconds.
Initial and final values are externally defined.
Fixed Point not available in this model