I have a TI-89 emulator in my android phone. I use it all the time from simple calculations to graphing. I think I might have used the calculus functions a coup

I have a TI-89 emulator in my android phone. I use it all the time from simple calculations to graphing. I think I might have used the calculus functions a couple of times. Anyway, it's really convenient and now I wouldn't even think about carrying around another device that only does what a calculator does.