Looks like a cool library. I'm curious why the Android calculator app needs reliable exact equality tests. It doesn't appear to have an equality test function.
Edit: the paper claims that you need exact equality tests to avoid printing unnecessary zeros at the end of decimal expansions, among other things.
Interesting that this work was done by Hans-J. Boehm, better known for the widely used Boehm garbage collector.
The equality test is equivalent to deciding if something is 0.
You can probably ask the app to calculate sqrt(2) * sqrt(2). If that doesn't show a 2 as answer, you've lost.
Same goes for sin(arcsin(1/2)). You want the exact answer.
Edit: the paper claims that you need exact equality tests to avoid printing unnecessary zeros at the end of decimal expansions, among other things.
Interesting that this work was done by Hans-J. Boehm, better known for the widely used Boehm garbage collector.