4 ms·

IEEE floating-point is disgusting. The non-determinism and illusion of accuracy is just wrong. I use integer or fixed-point decimal if at all possible. If the

IEEE floating-point is disgusting. The non-determinism and illusion of accuracy is just wrong. I use integer or fixed-point decimal if at all possible. If the algorithm needs floats, I convert it to work with integer or fixed-point decimal instead. (Or if possible, I see the decimal point as a "rendering concern" and just do the math in integers and leave the view to put the decimal by whatever my selected precision is.)

saagarjha 7y ago
IEEE is deterministic and (IMO) quite well thought-out. What specifically do you not like about it?
- pmarreck 7y ago
  The fact that the most trivial floating-point addition of 0.1 + 0.2 = 0.300000000000004 was insufficient to make this seem HUMAN-nondeterministic to you? (I mean sure, if you thoroughly understood the entire spec, you might not be surprised by this result, but many people would be! Otherwise the original post and website would not exist, no?) It’s kind of a hallmark of bad design when you have to go into a long-winded explanation of why even trivial use-case examples have “surprising” results.
  - saagarjha 7y ago
    You don't need to thoroughly understand the entire spec, nor do you need to know that 0.1 + 0.2 = 0.300000000000004. "Computers can't really represent floating point numbers exactly" is generally good enough. (Also: you added "human" as a qualifier; you didn't have that before so I responded to your statement as it was written.)
  - jcranmer 7y ago
    ⅓ to 3 decimal places is 0.333. 0.333 + 0.333 = 0.666, which is not ⅔ (to 3 decimal places, that is 0.667). That is all that is happening with the 0.1 + 0.2. The word you're looking for is "surprising," which is a far cry from non-deterministic. IEEE 754 is so thoroughly deterministic that there exists compiler flags whose sole purpose is to say "I don't care that my result is going to be off by a couple of bits from IEEE 754."
virtualparrot 7y ago
I agree with this view, there's nothing more disgusting than non-determinism. The way computers rely on assumptions for the accuracy of a floating number is one that's contrary to the principles of logical thinking.
- saagarjha 7y ago
  > The way computers rely on assumptions The way people rely on assumptions.
kstrauser 7y ago
Depends on the field. 99.9000000001% of the time, the stuff I do is entirely insensitive to anything after the third decimal point. And for my use cases, IEEE 754 is a beautiful stroke of genius that handles almost everything I ask from it. That's generally the case for most applications. If it wasn't, it wouldn't be so overwhelmingly universally used. But again, there are clearly plenty of use cases where it's insufficient, as you can vouch. I still don't think you can call it "disgusting", though.
deleted 7y ago
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enriquto 7y ago
you may dislike IEEE floats for many reasons, but not for being non-deterministic. Their operations are described by completely deterministic rules. Fixed point is perfectly OK, if all your numbers are within a few orders of magnitude (e.g. money)

saagarjha 7y ago

IEEE is deterministic and (IMO) quite well thought-out. What specifically do you not like about it?

pmarreck 7y ago
The fact that the most trivial floating-point addition of 0.1 + 0.2 = 0.300000000000004 was insufficient to make this seem HUMAN-nondeterministic to you? (I mean sure, if you thoroughly understood the entire spec, you might not be surprised by this result, but many people would be! Otherwise the original post and website would not exist, no?) It’s kind of a hallmark of bad design when you have to go into a long-winded explanation of why even trivial use-case examples have “surprising” results.
- saagarjha 7y ago
  You don't need to thoroughly understand the entire spec, nor do you need to know that 0.1 + 0.2 = 0.300000000000004. "Computers can't really represent floating point numbers exactly" is generally good enough. (Also: you added "human" as a qualifier; you didn't have that before so I responded to your statement as it was written.)
- jcranmer 7y ago
  ⅓ to 3 decimal places is 0.333. 0.333 + 0.333 = 0.666, which is not ⅔ (to 3 decimal places, that is 0.667). That is all that is happening with the 0.1 + 0.2. The word you're looking for is "surprising," which is a far cry from non-deterministic. IEEE 754 is so thoroughly deterministic that there exists compiler flags whose sole purpose is to say "I don't care that my result is going to be off by a couple of bits from IEEE 754."

virtualparrot 7y ago

I agree with this view, there's nothing more disgusting than non-determinism. The way computers rely on assumptions for the accuracy of a floating number is one that's contrary to the principles of logical thinking.

saagarjha 7y ago
> The way computers rely on assumptions The way people rely on assumptions.

kstrauser 7y ago

Depends on the field. 99.9000000001% of the time, the stuff I do is entirely insensitive to anything after the third decimal point. And for my use cases, IEEE 754 is a beautiful stroke of genius that handles almost everything I ask from it. That's generally the case for most applications. If it wasn't, it wouldn't be so overwhelmingly universally used. But again, there are clearly plenty of use cases where it's insufficient, as you can vouch. I still don't think you can call it "disgusting", though.

deleted 7y ago

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enriquto 7y ago

you may dislike IEEE floats for many reasons, but not for being non-deterministic. Their operations are described by completely deterministic rules. Fixed point is perfectly OK, if all your numbers are within a few orders of magnitude (e.g. money)