9 replies to this topic

[ebernerd]

So, I'm programming a sign. Amazing right?

I am printing the time of the world on that sign, but it prints something along the lines of "14.582" (basically, it prints 3 digits after the period).

Is there any way to make it so that it prints "14.6" (1 digit after the period)?

Any help is much appreciated.

[KingofGamesYami]

math.ceil() rounds to the nearest integer (up), math.floor() rounds down. I would write something like this (note - I have not tested this):

function round( num, place ) --#num is the decimal (eg. 14.582), place is the decimal place (eg 1)
 local wNum = num * ( 10^place ) --#make it an integer
 local low = math.floor( wNum ) --#find the high/low round
 local high = math.ceil( wNum )
 local lDiff = math.abs( wNum - low ) --#find the difference
 local hDiff = math.abs( high - wNum )
 local minDiff =  math.min( lDiff, hDiff ) --#find the lowest difference
 if minDiff == hDiff then --#return the correct number
  return high / (10^place)
 else
  return low / (10^place)
 end
end

Edited by KingofGamesYami, 14 August 2014 - 01:09 AM.

[theoriginalbit]

while KingofGamesYami's solution does work, it is very verbose, a simpler solution would be to do the following

local function round( num, idp )
  local mult = 10^(idp or 0)
  if num >= 0 then
    return math.floor(num * mult + 0.5 ) / mult
  end
  return math.ceil(num * mult - 0.5) / mult
end

[KingofGamesYami]

theoriginalbit, on 14 August 2014 - 01:17 AM, said:

while KingofGamesYami's solution does work, it is very verbose, a simpler solution would be to do the following

local function round( num, idp )
  local mult = 10^(idp or 0)
  if num >= 0 then
	return math.floor(num * mult + 0.5 ) / mult
  end
  return math.ceil(num * mult - 0.5) / mult
end

...wow

[Bomb Bloke]

... and that's without a ternary.

[theoriginalbit]

using the ternary operator in this instance, while making it more concise, would definitely decrease readability...

[natedogith1]

theoriginalbit, on 14 August 2014 - 01:17 AM, said:

while KingofGamesYami's solution does work, it is very verbose, a simpler solution would be to do the following

local function round( num, idp )
  local mult = 10^(idp or 0)
  if num >= 0 then
    return math.floor(num * mult + 0.5 ) / mult
  end
  return math.ceil(num * mult - 0.5) / mult
end

could it not just be this?

local function round(num,idp)
  local mult=10^(idp or 0)
  return math.floor(num * mult + 0.5 ) / mult
end

[Bomb Bloke]

Depends whether the time ever goes negative, I suppose.

[natedogith1]

I only see a difference when the fractional part of num is 0.5, at which point as far as I can tell rounding is allowed to go either way

[MKlegoman357]

There is a built-in function called textutils.formatTime wich converts the output from os.time to a human-readable format, for example, if os.time returns 14.5 then textutils.formatTime may produce 14:30 or 2:30 pm if you tell it to use 12-hour format.