interpolate (0,1),(0.1,1),(0.5,1),(0.9,1),(1,1),(1.03,2),(1.5,2),(1.8,2),(2,2),(2.3,3),(3,3),(3.2,4)

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.