For arduino, look into the map() function, it maps a range, over a given range
arduino.cc/reference/en/language/functions/math/map
From the top of my head it will be something like:
NewKnobValue = map(KnobAnalogueValue, -100, -99.9992370605, 0, 100);
That will make your -100 to -99.9992370605 return its equavalent of between 0 to 100. (-100 being zero and 100 being -99.9992370605)
Thus, you can use decent numbers for Construct :)