How would I pick a random number between 0.9 and 1.1?

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#1

I am making a script that plays a Sound every time the player’s Humanoid takes damage. The PlaybackSpeed of the Sound is supposed to randomly change to any number between 0.9 and 1.1, but I currently do not know how to do this without setting up an excruciatingly long table of possible values. I tried using a solution I Googled (there were little to no results) that used math.random, but I obviously did something wrong because it is picking numbers outside of the range:

Ouch.PlaybackSpeed = math.random(9)/11
One of the random outputs: 0.090909093618393

May anyone please explain how I could fix this?

Edit: There are multiple solutions:

Integars:
https://devforum.roblox.com/t/how-would-i-pick-a-random-number-between-0-9-and-1-1/620169/3?u=

Real numbers:

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#4

@Nerkonl @ArrantNickel Neither of these work, I’m still getting 0 or something like 0.89. Or is it supposed to look like this?

#6 
local RNG = Random.new(tick())
for i = 1, 10 do
	local random_number = RNG:NextNumber(0.9, 1.1)
	print(("Our next random number is: %s"):format(random_number))
end

Output will be something like:

 Our next random number is: 1.0571754411884
  Our next random number is: 0.97491074296206
  Our next random number is: 0.97687826467788
  Our next random number is: 0.96483255566682
  Our next random number is: 1.0297381383331
  Our next random number is: 1.0022596426323
  Our next random number is: 0.98034686206397
  Our next random number is: 1.0964522742403
  Our next random number is: 0.99467616375973
  Our next random number is: 0.92166707067802
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#8

It doesn’t need to be 5 lines, that was purely just to demonstrate it works :slight_smile:

local RNG = Random.new(tick())

--> When we need a random number:
print(RNG:NextNumber(0.9, 1.1))

--[!] or, even:

print(Random.new():NextNumber(0.9, 1.1))
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#9 
function genRandom(min, max)
     return min + math.random() * (max - min)   
end
14 Likes
#11

I imagine the issue with your solution, although functional, only returns a pseudo-random integer. This is due to the way math.random functions - when given two integers as an argument it returns a uniformally generated random integer within that range.

That’s why @Auxintic created a function to get a random number with more digits by not passing any arguments to the math.random function. When called with no arguments it returns a uniform, real number between 0 to 1

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#12

Yours kind of works, but it only seems to get 0.9, 1 and 1.1. Unrelated to your solution, but for some reason the actual playbackspeed looks different:
(Actual playbackspeed on bottom)
Screen Shot 2020-06-10 at 4.35.07 PM

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#14

@Mystyle48
I imagine this may be some kind of floating point error, or possibly some other issue within the Engine.

@ArrantNickel

Again, it’s not that solution doesn’t work - it’s just that OP wanted a real number, not an integer and your solution provides only integers when calling math.random(9, 11) therefore you can only get 0.9, 1, and 1.1 when dividing the result by 10. You can learn more here: math | Documentation - Roblox Creator Hub

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#15

local num = 0.9 + math.random()*0.2

#16

@ArrantNickel Do what works for you, but I’ll be using @Isocortex and @Auxintic’s solutions for this. Thank you all for helping!

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#17 
local Rand = Random.new()
print(Rand:NextNumber(0.9,1.1))

Using the Random API : Random | Documentation - Roblox Creator Hub

Also, for future reference - the usage of math.random is math.random(min, max).

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