How does your programming language handle “minus zero” (-0.0)?
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Re: How does your programming language handle “minus zero” (-0.0)?
#2Does anyone have a good example of a programming problem where we _need_ signed zero? Or where it makes things significantly simpler? As far as I know, there is no distinction between -0 and +0 in math, so I have never really understood why this is a thing in computers.
Re: How does your programming language handle “minus zero” (-0.0)?
#3Does anyone have a good example of a programming problem where we _need_ signed zero? Or where it makes things significantly simpler? As far as I know, there is no distinction between -0 and +0 in math, so I have never really understood why this is a thing in computers.
Negative zero was introduced because of branch cuts: https://people.freebsd.org/~das/kahan86branch.pdf
Re: How does your programming language handle “minus zero” (-0.0)?
#4Does anyone have a good example of a programming problem where we _need_ signed zero? Or where it makes things significantly simpler? As far as I know, there is no distinction between -0 and +0 in math, so I have never really understood why this is a thing in computers.
Amusingly enough the Apple Watch reports temperature as 0° and sometimes as -0°, I've not determined what causes that, perhaps rounding around 0?
Re: How does your programming language handle “minus zero” (-0.0)?
#5Elixir does not distinguish signs in zero, 0.
Therefore; -0.0 + 2.0 = 2.0 and 0.0 + 2.0 = 2.0
Re: How does your programming language handle “minus zero” (-0.0)?
#6Elixir does not distinguish signs in zero, 0. Therefore; -0.0 + 2.0 = 2.0 and 0.0 + 2.0 = 2.0
Isn't that true for all correct implementations of negative zero? It's still a neutral for addition
Re: How does your programming language handle “minus zero” (-0.0)?
#7Does anyone have a good example of a programming problem where we _need_ signed zero? Or where it makes things significantly simpler? As far as I know, there is no distinction between -0 and +0 in math, so I have never really understood why this is a thing in computers.
Computers (obviously) have to approximate the majority of actual mathematical numbers, as they do not have infinite storage.
If you've got two numbers, +0.0000001 and -0.0000001, but you can't represent that precision, can you see how it's less bad to round to +0.0000 and -0.0000 rather than to just 0.0000? It's encoding strictly more information.
Re: How does your programming language handle “minus zero” (-0.0)?
#8Elixir does not distinguish signs in zero, 0. Therefore; -0.0 + 2.0 = 2.0 and 0.0 + 2.0 = 2.0
I don't understand what you think a result could look like here that does distinguish the sign? What are you expecting? -2.0? That doesn't make any sense. 2.0 is the correct answer under all circumstances as far as I can see.
Re: How does your programming language handle “minus zero” (-0.0)?
#9Does anyone have a good example of a programming problem where we _need_ signed zero? Or where it makes things significantly simpler? As far as I know, there is no distinction between -0 and +0 in math, so I have never really understood why this is a thing in computers.
Amusingly enough the Apple Watch reports temperature as 0° and sometimes as -0°, I've not determined what causes that, perhaps rounding around 0?
Sometimes the sign is used to indicate which "direction" the temperature is moving. If it was -10° overnight and it's -0° now, the puddles outside will still be frozen. If it was 10° overnight and it's 0° now, the puddles will still be liquid.
(Edit: no idea whether this applies to the Apple watch, it's just a use case for -0 with regards to temperature.)
Re: How does your programming language handle “minus zero” (-0.0)?
#10Does anyone have a good example of a programming problem where we _need_ signed zero? Or where it makes things significantly simpler? As far as I know, there is no distinction between -0 and +0 in math, so I have never really understood why this is a thing in computers.
Amusingly enough the Apple Watch reports temperature as 0° and sometimes as -0°, I've not determined what causes that, perhaps rounding around 0?
Probably not even rounding, but just printf. The following works on my zsh:
$ printf '%.0f°\n' 0.3
0°
$ printf '%.0f°\n' -0.3
-0°