Rounding

Harrison

In programming, rounding down to the ones place is important.. think hours to minutes, dollars to change.. etc.
I made a exel spreadsheet that did just that-

in psudocode: x=5.223 y=rounddown(x) (to the nearest ones place) x=x-y print(x..":"..y)

(in a perfect world would yield 5:0.22)
but when i attempt to round in lua there is no simple round function unlike exel..
math.floor just takes my number to zero
so does this:

function round(num) if num >= 0 then return math.floor(num+.5) else return math.ceil(num-.5) end end

also yields 0
which i got from http://lua-users.org/wiki/SimpleRound
First, why?
Next, what should i be doing?

amin13a

It works for me:
in main.lua (and no other code):

function round(num)
if num >= 0 then return math.floor(num+.5)
else return math.ceil(num-.5) end
end
print(round(2.85))

Result:
main.lua is uploading.
Uploading finished.
3

HubertRonald

Hi @Harrison

I use the next code:

local floor = math.floor function round(val, decimal) if (decimal) then return floor( (val * 10^decimal) + 0.5) / (10^decimal) else return floor(val+0.5) end end     print(math.pi) print(round(math.pi)) print(round(math.pi,4))   --[[ I get: 3.1415926535898 3 3.1416 ]]

In your case I would do the following

local x = 5.223 -- input local y = round(x,2) -- define numbers of decimals x = round(x) -- rounddown integer y = y - x -- get decimals print(table.concat({x,":",y})) -- it's more fast!   --[[ I get: 5:0.22 ]]

I hope than it can hep you >-

Harrison

thanks, that helps a lot. Now i just need to fix the results when something with a decimal over 0.5 is passed (ex. 5.55 results in 6 and -0.45)
edit:
fixed by doing this after your second block of code you posted-

if y < 0 then --checks to see if the rounding code rounded up y = 1 + y --takes the negative y and finds its positive opposite x=x-1 --removes 1 from x to make up for upward round end

man this concept is hard to wrap my mind around!

HubertRonald

@Harrison I'm glad you've got it >-