Small-data computing: Correct calculator arithmetic

Communications of the ACM (CACM Vol. 60 No. 8, August 2017), 60(2017), pp. 44-49


Calculators conventionally use some flavor of fixed precision floating point arithmetic. The bundled Android 6.0 Marshmallow calculator instead uses demand-drive evaluation or “constructive real” arithmetic to guarantee fully accurate results. We explain why this matters, the opportunities it creates, and the challenges in incorporating constructive real arithmetic in a tool aimed at a very broad audience.