producing sine wave variable in amplitude and frequency How to produce a sine wave with variable frequency and variable amplitude?
I found a library to produce variable frequency called sinwave but not produce variable amplitude (I want -2V to 2V amplitude)
You can use a digital potentiometer as a programmable attenuator or as a feedback element in a programmable gain amplifier circuit.

See references  at arduino.cc regarding interfacing an AD5171 or AD5206 to Arduinos.