Inaccurate in Developer Help

ID:148936
 
Aug 10 2002, 3:51 pm
mob/var/hp = 0 as num

mob/Stat()
..()
statpanel("sdafd")
stat("HP:","[num2text(src.hp,99999999)]")
mob/verb/AddHP(N as num)
hp += N

mob/verb/Thingy()
src << src.hp


But the thing is I add this to the hp(99999999), and this is what I see in the statpanel.. 100000000

Why when I add 0 to 99999999 I get 100000000. Would that make the BYOND system inaccurate with adding? Please give me the 411
#1 Aug 10 2002, 4:21 pm
Super16 wrote:
mob/var/hp = 0 as num

mob/Stat()
..()
statpanel("sdafd")
stat("HP:","[num2text(src.hp,99999999)]")
mob/verb/AddHP(N as num)
hp += N

mob/verb/Thingy()
src << src.hp


But the thing is I add this to the hp(99999999), and this is what I see in the statpanel.. 100000000

Why when I add 0 to 99999999 I get 100000000. Would that make the BYOND system inaccurate with adding? Please give me the 411

Change

>   stat("HP:","[num2text(src.hp,99999999)]")

to
>   stat("HP:",src.hp)


#2 Aug 10 2002, 4:25 pm
In response to Malver (#1)
I don't want it to display scientific notation. That's what num2text does. Do this and tell me what you get

mob/verb/Thing()
var/result = 0
var/thing = 99999999
result += thing
src << result

You will get 100000000. That's a problem.
#3 Aug 10 2002, 4:46 pm
It's not about adding. I believe it's about storage. A computer has a finite amount of bits to store things in. At a certain point, small differences are pretty much ignored. (It's not exactly a BYOND thing.)

world << "[99999999]" will output 1e+008 whether or not you add anything. So will 99999998. Those numbers are huge.
#4 Aug 11 2002, 8:21 am
In response to Super16 (#2)
Super16 wrote:
I don't want it to display scientific notation. That's what num2text does. Do this and tell me what you get

mob/verb/Thing()
var/result = 0
var/thing = 99999999
result += thing
src << result

You will get 100000000. That's a problem.

You can make your own proc for this; it will be limited to the accuracy of floating point, but it should suffice for this. With your own proc, you can also put in commas:
proc/num2text2(n,precision=6)
  var/t=""
  var/neg=(n<0)
  if(neg) n=-n
  var/digit
  if(n-round(n))
    t="."
    var/dec=n-round(n)
    while(dec && (precision--))
      dec*=10;digit=round(dec);dec-=digit
      t+="[digit]"
  while(dec)
    digit=dec%1000
    dec-=digit
    if(!dec) t="[digit][t]"
    else
      t=",[copytext("[digit+1000]",2)][t]"
      dec=round(dec/1000,1)  // account for rounding error
  if(neg) t="-[t]"
  return t

Lummox JR
#5 Aug 11 2002, 6:37 pm
In response to Lummox JR (#4)
Lummox JR wrote:
Super16 wrote:
I don't want it to display scientific notation. That's what num2text does. Do this and tell me what you get

mob/verb/Thing()
var/result = 0
var/thing = 99999999
result += thing
src << result

You will get 100000000. That's a problem.

You can make your own proc for this; it will be limited to the accuracy of floating point, but it should suffice for this. With your own proc, you can also put in commas:
proc/num2text2(n,precision=6)
>   var/t=""
>   var/neg=(n<0)
>   if(neg) n=-n
>   var/digit
>   if(n-round(n))
>     t="."
>     var/dec=n-round(n)
>     while(dec && (precision--))
>       dec*=10;digit=round(dec);dec-=digit
>       t+="[digit]"
>   while(dec)
>     digit=dec%1000
>     dec-=digit
>     if(!dec) t="[digit][t]"
>     else
>       t=",[copytext("[digit+1000]",2)][t]"
>       dec=round(dec/1000,1)  // account for rounding error
>   if(neg) t="-[t]"
>   return t

Lummox JR

You do know you will get an error. For dec being an undefined var. You defined for only under the if statement.. Just wanted to tell you that...