What two input functions satisify an output between 0 and 1? What are common functions that take two input variables and make the output between 0 and 1? 
Question is as simple as that, two inputs and one output, output needs to stay between 0 and 1!

This question is way way way way way way too broad. There are infinitelly many such functions.
Examples:


*

*$f(x,y)=|\sin(x)|$

*$f(x,y)=\sin^2(x)\sin^2(y)$

*$f(x,y)=1$

*$f(x,y) = e^{-x^2-y^2}$


There are many more. Without further details, it's hard to give a more accurate answer.
