seems like you're talking about several different things
- i think you're describing a class, not necessarily a library
- i don't see the update() identified in the .h, wouldn't it be the function used to update the value and shouldn't it be public and shouldn't it return the updated value
- don't see inputArray[] nor understand why you would need such
- not sure what you mean by value type -- the value provided to the class or the value maintained and returned. (why not just do everything with doubles)
- don't understand low, high and changeby. seems you would have a threshold above which you adjust the value by a large amount and below which you adjust by a small amount. are low/high the adjustment values or thresholds
- don't understand the purpose of a deadzone. is the deadzone around the threshold
- additional parameter (i.e. max, min can always be set in the constructor but need to be defined
- are there just 5 parameters: min, deltaLow, thresh, deltaHigh, max?