print((-200 * 2.55) + (255 * 2))
If you run this in studio it gives 5.6843418860808e-14 as the answer, what?
Is this a bug or is there something really simple here that I am missing?
The correct answer should be 0, no?
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the correct answer is 0
this is odd
local first = -200 * 2.55
local second = 255 * 2
print(first) --> -510
print(second) --> 510
print(first + second) --> 5.6843418860808e-14
Yeah something weirds going on, some lua engine expert will probably come on explain what’s happening.
print((-200 * 2.55) + (255 * 2))
print(-200 * 2.55 == -510, -200 * 2.55, 255 * 2)
print(-510 + 510)
OUTPUT
5.6843418860808e-14
false -510.0 510
0
why is this happening…
EDIT:
tested this on the lua demo page
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Ye, this been bugging me for awhile now, I posted here first in case there’s a specific reason why lua returns that
Either we’re all missing something really simple here or we’ll find out that this is a studio bug 
It’s likely just a floating point error. Realize that 5.6843418860808e-14 is equal to 0.000000000000056843418860808. It is odd to see a floating point error with those small numbers though 
.
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could it be a floating point error?
usually the decimals are smaller then that, but idk
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put the calculated number in an int value then print the int value value.
This is because the number is actually a negative number, it would be the same as doing 5.68 x 10^-14 (scientific notation).
The real number would be 0.000000000000056843.
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Today color3s were also facing this issue. When I tried changing the atmosphere color through a script I selected a color3 from the script itself but when I played everything was white and the atmosphere was set to 0,0,0
So to remove the stupid annoying decimal numbers, put it in an int value and print the intvalue’s value .
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the answer is 0. how that was really odd
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Okay, this is the last time I’m gonna say this, intvalue’s remove decimals so you can use them
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you could just use math.round instead of that
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Up to you, I’m only explaining why the equation is what it is.
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From the looks of it, its just a floating point error, normally multiplication and decimal based numbers cause this.
Its really:
0.000000000000056843418860808
But yeah pretty common in the sweet sweet 32 bit numbering system Lua has.
3 Likes
Decimal Rounding Errors. Roblox uses floats which can hold values from
1.7 Ă— 10^308 to 1.7 Ă— 10^308
Basically when calculating your result, the computer could not hold the decimal perfectly in binary(0101010)
Your number you got could be rounded to get your true result of zero but the result you got it really close to zero off by not much.
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0.000000000000056843418860808 was the result from the math, and while technically this is not true, it’s a major problem faced by all computer science people. This result is so close to 0.
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