On Data Types
Over, and over again: floating point does not exist in the part of the real world that computers actual interact with. I've built an (Intel) IEEE-754 emulator. If you don't know why I needed to specify Intel, then you don't really understand the standard. I've also done proofs of the accuracy of floating point computations.
If you are doing currency computations, you are working exclusively with integers. But not integers of the currency base, integers of the smallest denomination. (For the US dollar, this is a mill-- 0.1 cents)
If you are taking a reading from an instrument, you are getting a quantized result. Those translate to integers.
The problem is that we like to write contracts that require us to divide. See the "average daily balance" for credit cards, or the financial compacts that lead up to the Euro. But even then, when the computation is done, the results are integers.
Floating point is an abstraction with some really nasty leaks. If you are seriously concerned about last-bit accuracy in your computations, you are going to have to jump through some crazy hoops.
The fact that Excel, MATLAB and other PHB-level applications don't worry about it means that you better not either if you use these products.
Biting the hand that feeds IT
