Issues with doing math, numbers are too big and return inf

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#1

I am doing some math calculations with os.time() to calculate what I need to divide another value by just returns inf since it is bigger then the 2^53 limit or whatever, how can I fix this? (For reference this is what I am doing)

local time = os.time()
local g = math.pow(time, #key - i) -- 0-32
character * g -- num * g

then trying to undo it

local g = math.pow(time, #key - i);
g = character / g;
print(g) -- prints inf, should be the original "character" value...
#2

What is the value of character where it prints inf?

#3

Character is just a number in a string, I get each character in a string, if it is a number multiply it isn’t character that is the issue.

#4

If you put in a dummy value for character like 2, does it still print inf?

#5

Yes it does still print inf it is the os.time() I believe.

#6

That’s odd, I tried testing this myself with this script:

local time = os.time()
local g = math.pow(time, 32) 
local character = g * 2
print(character)
print(character/g)

And unless I’m misunderstanding your problem, everything should work fine, since it never prints inf. It’s not something with os.time().

#7

The only way I can replicate your error is by having the second argument of math.pow() be greater than 1.365. You should print #key - i to ensure that it really is -32. Unless you mean that it will count from 0 to 32 in which case, that’s the problem.

#8

i is a value that is counting from 32, to 0

#9

How large is #key
wow… why is the term 31-1chars not allowed? Sometimes I need a clarification in under that amount of chars and it’s a brief explanation of the extra characters. Ohh well, my mini rant was enough to get me past the minimum character limit

#10

Actually why do you need to use math.pow on time? I’m pretty sure that’s your issue, but without context I can’t really see why you need it. Can’t you just not encrypt the data? Then you wouldn’t need to unencrypt it.

#11

Here is encrypting:

for i = #key, 1, -1 do
				local character = string.sub(key, #key - i + 1, #key - i + 1); -- if #key is 10, and i = 7, then it is 4
                if #key - i + 1 > #key then
                    character = string.sub(key, #key, #key);
                end
				if tonumber(character) then
                    hashedKey[i] = character;
                    local g = math.pow(LockService.Salt[player.UserId], #key - i); -- if #key is 10, and i = 7, then it is 3
                    --local num = string.byte(character) * g;
					hashedKey[i] = character * g;

				else
					hashedKey[i] = character
                end 
            end

the “salt” is os.time(), basically the key to encrypting and decrypting
Decrypting:

for i = #key, 1, -1 do
            local character = key[i];
            print(character)
            if tonumber(character) then
                local g = math.pow(salt, #key - i); -- 10, i = 7, g = 3
                g = character / g;
                print(g)
                decrypt = decrypt .. tostring(g);
            elseif character ~= nil then
                decrypt = decrypt .. character;
                print(character, "string")
            else
                print("Neither?", character);
            end
        end
#12

This is not unusual. os.time() returns a fairly large number, around ten digits, whose negative power is a number so small that it exceeds the lower limit of an IEEE 64-bit floating-point number. It is so small that it is simply interpreted as zero. So any number divided by zero is Infinity.

You might consider using a fraction of os.time() or scaling it in some way to avoid that overflow.

#13

the highest number you can get is 2147483647

( I think )

#14

Roblox’s limits are higher than that; Some numbers I have seen are upwards of QD

edit: NumberValue
They use 64 bit for number saving, or about 9QD

1 Like
#16

Yeah tried that, even with 2 it prints inf…