OpenEuphoria

Re: rounding problem

• Posted by Juergen Luethje <j.lue at gmx.de> Oct 24, 2006
• 513 views

These are the rounding functions that I use:

global type nonnegative_int (object x)
   if integer(x) then
      return x >= 0
   end if
   return 0             -- FALSE
end type

global function round_half_even (object x, nonnegative_int digits)
   -- rounding according to the IEEE standard
   -- in: x     : (sequence of) number(s) to round
   --     digits: desired number of decimal places
   atom p, ret

   if atom(x) then
      p = power(10, digits)
      ret = floor(x*p + 0.5)
      if remainder(ret, 2) then
         ret -= 1
      end if
      return ret/p
   end if

   for i = 1 to length(x) do
      x[i] = round_half_even(x[i], digits)
   end for
   return x
end function

global function round_half_up (object x, nonnegative_int digits)
   -- "commercial rounding"
   -- in: x     : (sequence of) number(s) to round
   --     digits: desired number of decimal places
   atom p

   if atom(x) then
      p = power(10, digits)
      if x >= 0 then
         return  floor( x*p + 0.5)/p
      else
         return -floor(-x*p + 0.5)/p
      end if
   end if

   for i = 1 to length(x) do
      x[i] = round_half_up(x[i], digits)
   end for
   return x
end function


-- Demo
? round_half_even( 2.65, 1)
? round_half_up  ( 2.65, 1)
? round_half_even( 2.75, 1)
? round_half_up  ( 2.75, 1)
puts(1, "\n")
? round_half_even(-2.65, 1)
? round_half_up  (-2.65, 1)
? round_half_even(-2.75, 1)
? round_half_up  (-2.75, 1)

Regards,
   Juergen