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0 pointspgwhalen9mo ago0 comments

I agree overall but my take is that it shows more ignorance about the domain of finance (or a particular subdomain) than it does about floating-point ignorance.

It’s really more of a concern in accounting, when monetary amounts are concrete and represent real money movement between distinct parties. A ton of financial software systems (HFT, trading in general) deal with money in a more abstract way in most of their code, and the particular kinds of imprecision that FP introduces doesn’t result in bad business outcomes that outweigh its convenience and other benefits.

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munch1179mo ago

FP does not introduce imprecision. Quite the contrary: The continuous rounding (or truncation) triggered by using scaled integers is what introduces imprecision. Whereas exponent scaling in floating point ensures that all the bits in the mantissa are put to good use.

It's a trade-off between precision and predictability. Floating point provides the former. Scaled integers provide the latter.

pgwhalenOP9mo ago

I was using imprecision in a more general and less mathematical sense than the way you’re interpreting it, but yes this is a good point about why FP is useful in many financial contexts, when the monetary amount is derived from some model.

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0 pointspgwhalen9mo ago0 comments

I agree overall but my take is that it shows more ignorance about the domain of finance (or a particular subdomain) than it does about floating-point ignorance.

0 comments

munch1179mo ago

It's a trade-off between precision and predictability. Floating point provides the former. Scaled integers provide the latter.

pgwhalenOP9mo ago

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