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Stop using floats (lemmy.world)
submitted 1 month ago by nifty to c/[email protected]
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[-] [email protected] 17 points 1 month ago

I have been thinking that maybe modern programming languages should move away from supporting IEEE 754 all within one data type.

Like, we've figured out that having a null value for everything always is a terrible idea. Instead, we've started encoding potential absence into our type system with Option or Result types, which also encourages dealing with such absence at the edges of our program, where it should be done.

Well, NaN is null all over again. Instead, we could make the division operator an associated function which returns a Result and disallow f64 from ever being NaN.

My main concern is interop with the outside world. So, I guess, there would still need to be a IEEE 754 compliant data type. But we could call it ieee_754_f64 to really get on the nerves of anyone wanting to use it when it's not strictly necessary.

Well, and my secondary concern, which is that AI models would still want to just calculate with tons of floats, without error-handling at every intermediate step, even if it sometimes means that the end result is a shitty vector of NaNs, that would be supported with that, too.

[-] [email protected] 10 points 1 month ago

I agree with moving away from floats but I have a far simpler proposal... just use a struct of two integers - a value and an offset. If you want to make it an IEEE standard where the offset is a four bit signed value and the value is just a 28 or 60 bit regular old integer then sure - but I can count the number of times I used floats on one hand and I can count the number of times I wouldn't have been better off just using two integers on -0 hands.

Floats specifically solve the issue of how to store a ln absurdly large range of values in an extremely modest amount of space - that's not a problem we need to generalize a solution for. In most cases having values up to the million magnitude with three decimals of precision is good enough. Generally speaking when you do float arithmetic your numbers will be with an order of magnitude or two... most people aren't adding the length of the universe in seconds to the width of an atom in meters... and if they are floats don't work anyways.

I think the concept of having a fractionally defined value with a magnitude offset was just deeply flawed from the get-go - we need some way to deal with decimal values on computers but expressing those values as fractions is needlessly imprecise.

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this post was submitted on 26 Feb 2024
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