[saagarjha]

This is not always a safe assumption (in certain scenarios floating point results being nondeterministic has the possibility to introduce bugs and security issues) and is also a kind of sad way to look at the world. The response to "I don't understand how this works" should not be to adopt an incorrect viewpoint, but to know the limitations of your understanding.

[TylerE]

It’s not that I don’t understand, it’s that I do. Floats are inherently lossy representations. Yes, this means the more operations you perform on a float input, the fuzzier the value is.You ignore that harsh reality at your peril. If you find engineering rigor sad, I don’t know what to tell you.

[saagarjha]

"Floats are not deterministic" is not engineering rigor, it's just wrong. They are specified precisely by IEEE-754 in how they must behave and which operations are allowed to produce which results.

[TylerE]

IEEE 754 conforming floats conform to IEEE-754. If they actually conform. Low end devices with shitty software implementations often get the hard edge cases wrong.

[saagarjha]

Yes and when that happens it is important to know what went wrong rather than just handwaving "oh it's that float stuff again I can't trust it".

[jacobolus]

> the more operations you perform on a float input, the fuzzier the value is

No, any float always precisely represents a specific number. The issue is that only a finite number of numbers are representable.

Some algorithms are poorly conditioned and when implemented using floating point arithmetic will lead to a result that is different than what you would get in idealized real number arithmetic. That doesn't make any floating point value "fuzzy".

[aidenn0]

> No, any float always precisely represents a specific number. The issue is that only a finite number of numbers are representable.

A float always precisely represents a specific number, but that number is not always precisely the equal to the algebraic result of the operations performed (even when ignoring transcendental and irrational functions). This should be obvious since there is no limit to rational numbers, but finite floating point numbers.

If you design your algorithms very carefully, you can end up with the ratio of the output of your algorithm to the ratio of the algebraic result close to unity over a wide domain of inputs.

[otabdeveloper4]

Irrational numbers cannot have an exact representation in digital bits. (Computers use rational numbers with modular arithmetic under the hood.)

[saagarjha]

Yes I am aware of this fact