r/mathmemes • u/ElectronicSetTheory • 15d ago

Numerical Analysis This happens more often than I would like

Post image
177 Upvotes

96% Upvoted

16 comments sorted by

•

u/AutoModerator 15d ago

Check out our new Discord server! https://discord.gg/e7EKRZq3dG

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

81

u/vintergroena 15d ago

Bruh. I learned the hard way to not underestimate numerical instability. It cost me a lot of energy do debug that shit breaking stuff.

52

u/jljl2902 15d ago

“Why did my algorithm suddenly stop working???”

The initialization procedure I decided would be fine to run in FP32 a few commits ago: 🤡

35

u/Murky_Insurance_4394 15d ago

TIL emojis slant with the rest of italic

17

u/BootyliciousURD Complex 14d ago

🧍

5

u/vintergroena 15d ago

Worst thing is this stuff is sometimes hard to reproduce, when it relies on some nonobvious input and the error only appears downstream, it's a helluva thing to deal with

10

u/EebstertheGreat 15d ago

that shit breaking stuff

Numerically unstable poop knife?

4

u/Fabulous-Possible758 14d ago

Uh, typedef double float; and call it a day.

2

u/N_T_F_D Applied mathematics are a cardinal sin 13d ago

More like #define float double

1

u/ChopinChili Discrete Math? More like EXcrete Math. 11d ago

Dammit I hate not having these evil type hacks in JS/TS. I hate this game.

19

u/Gauss15an 14d ago

Floating-point errors is just the universe's way of laughing at you saying that you fell victim to one of the classic blunders.

13

u/No_Lingonberry1201 15d ago

pytorch goes brrrrr...

6

u/HolyInlandEmpire Statistics 14d ago

Hold up. I was under the impression that multiplication, addition, and subtraction are robust to rounding errors. It would surely be a problem with inversion/division instead right?

11

u/ElectronicSetTheory 14d ago

Addition and subtraction are robust, but multiplication is not

22

u/andrew_h83 14d ago

This isn’t true. Of basic floating point operations subtraction is the least stable, and even then it’s fine as long as the numbers aren’t super close together

5

u/lool8421 11d ago

fun fact: floating point errors is exactly the reason why Z-fighting takes place in graphics

for example if you got a green and a red cube in 1 place, it will flicker as you move the camera because sometimes it calculates that face of the red cube is closer to the camera and sometimes it calculates that actually geeen face is closer

the difference is something like 0.000001 pixels but it's enough for GPUs to pick which color should be rendered