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[-] halvar@lemm.ee 44 points 1 year ago* (last edited 1 year ago)

well 0.9999... is actually 1 because

x = 0.9999...

10x = 9.9999...

10x (9.9999...) - x (0.9999...) = 9

9x = 9

x = 1

so 0.9999... is 1
[-] RedditWanderer@lemmy.world 44 points 1 year ago

This is muuuch better demonstrated by

1/3 = .33... 2/3 = .66... 3/3 = 0.99...

"Repeating" matters in approximations

[-] exscape@kbin.social 26 points 1 year ago

Yes, but 0.99999999999999999999 isn't 0.999... and therefore not 1, so it's still wrong.

[-] halvar@lemm.ee 9 points 1 year ago

The software is wrong yes. I just had to share this information.

[-] expatriado@lemmy.world 7 points 1 year ago

your 4th line reads as 10x^2 - x^2 = 9

[-] halvar@lemm.ee 4 points 1 year ago

You know I didn't mean it like that, but you are technically right.

[-] thedoodlenoodle@lemmy.sdf.org 3 points 1 year ago

First thing that came to mind was this video by SingingBanana.

Great maths channel and he is a frequently on numberphile as well.

[-] nogrub@lemmy.world 40 points 1 year ago

it's almost like computers are not that accurate when calculating floating point numbers

[-] afraid_of_zombies@lemmy.world 6 points 1 year ago

About a year ago I ended up with a floating point value that was something like 1.0000000000078 when it should have been 1. Tore my hair out for hours trying to get the piece of crap embedded vendor locked device to just make it 1.

[-] macrocephalic@lemmy.world 4 points 1 year ago

It's almost like some useless person created a variable with a distinct set unlikely to be higher than the hundreds as a floating point - when it obviously should have been an int.

[-] WhiskyTangoFoxtrot@lemmy.world 10 points 1 year ago

Nah, it makes sense to use a floating point number here, since unless the test is marked out of a factor of 100 then there will likely be a fractional value as the final percentage. The mistake was not rounding the final displayed value.

[-] Slatlun@lemmy.ml 17 points 1 year ago
[-] ChicoSuave@lemmy.world 2 points 1 year ago

Blame the font

[-] GigaWerts@lemmy.eco.br 16 points 1 year ago* (last edited 1 year ago)

The issue here lies in how it calculates each correct answer value, which is set at 1/15. This approach introduces an approximation error. When you sum all these values together, the total doesn't quite reach 1.

edit: It's actually 1/19 for each question

(1/19)*19 = 0,9999999991

[-] AmidFuror@kbin.social 2 points 1 year ago

But then the score should be 126.666666666667%.

[-] austin@aussie.zone 13 points 1 year ago

Looks like a floating point error

[-] xpinchx@lemmy.world 9 points 1 year ago

Heh, our WMS does this. Picking through a batch and we go from 19% complete to 22.573729384674829273747% complete.

[-] momocchi@lemmy.world 8 points 1 year ago

19.0000000000f/19.0000000000f

[-] FlyingSquid@lemmy.world 7 points 1 year ago

Computer: "You still suck, puny fleshbag."

Just be glad you didn't get an, "100% required to pass" error

[-] AllNewTypeFace@leminal.space 7 points 1 year ago

Presumably because only God can be perfect

[-] candyman337@sh.itjust.works 7 points 1 year ago

Is that actually mathematically the same number

[-] affiliate@lemmy.world 9 points 1 year ago* (last edited 1 year ago)

the pedantic answer is that, from a rigorous perspective, 99.9999999999999% isn't the same as 100% because the decimals don't repeat forever. but a more practical answer would be that they are the same number. because of how computers (usually) round numbers, the stuff showing up after the 8th decimal place is (usually) junk that can be ignored.

an interesting example of this idea in practice has to do with the irrational number π, which nasa only approximates to 15 decimal places because that's more than enough for most of the calculations they do (the linked page gives a better and more detailed explanation).

[-] candyman337@sh.itjust.works 3 points 1 year ago* (last edited 1 year ago)

Thank you for the very informative comment and article :)

[-] austinfloyd@ttrpg.network 2 points 1 year ago
this post was submitted on 02 Sep 2023
531 points (98.9% liked)

Software Gore

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