Rounding or flooring

[DorkeyDear]

It seems that the Round and RoundTo functions round down, or take the floor (i think its refered to as that, I don't know), but should round according if it is >= .5 or  < .5. A Floor function should round down.
Sry if its not called floor, i can't remember off the top of my head.

[chrisgbk]

It seems that the Round and RoundTo functions round down, or take the floor (i think its refered to as that, I don't know), but should round according if it is >= .5 or  < .5. A Floor function should round down.
Sry if its not called floor, i can't remember off the top of my head.

The round functions don't round down, they round to even, as per the IEEE754 floating point specification (Statistically, this results in better distribution of data). Rounding down is floor, rounding up is ceiling, rounding as you want it is either, depending on how you round numbers < 0, either round towards infinite(same as ceiling) or round away from 0.

I'll talk to EnEsCe about possibly changing this.

[rhpot03]

Code: [Select]

Function RoundDown(num:Extended) : Integer;
begin
  Result := round(num - 0.4999999);
end;and similarly...

Code: [Select]

Function RoundUp(num:Extended) : Integer;
begin
  Result := round(num + 0.4999999);
end;

[chrisgbk]

Code: [Select]

Function RoundDown(num:Extended) : Integer;
begin
  Result := round(num - 0.4999999);
end;and similarly...

Code: [Select]

Function RoundUp(num:Extended) : Integer;
begin
  Result := round(num + 0.4999999);
end;

These are not guaranteed to work; as an example, using RoundUp with 2.0000001 will result in an answer of 2; similarily using RoundDown with 3.9999999 will result in an answer of 4.

[urraka]

Code: [Select]

function RoundDown(num:Extended): Integer;
begin
    Result := round(num);
    if Result > num then
        Result := Result - 1;
end;


Code: [Select]

function RoundUp(num:Extended): Integer;
begin
    Result := round(num);
    if Result < num then
        Result := Result + 1;
end;

I think this could work.

[chrisgbk]

Code: [Select]

function RoundDown(num:Extended): Integer;
begin
    Result := round(num);
    if Result > num then
        Result := Result - 1;
end;


Code: [Select]

function RoundUp(num:Extended): Integer;
begin
    Result := round(num);
    if Result < num then
        Result := Result + 1;
end;

I think this could work.

rounddown(2.4) = 2
rounddown(2.5) = 2
rounddown(2.6) = 3 - 1 = 2
rounddown(3.4) = 3
rounddown(3.5) = 4 - 1 = 3
rounddown(3.6) = 4 - 1 = 3

roundup(2.4) = 2 + 1 = 3
roundup(2.5) = 2 + 1 = 3
roundup(2.6) = 3
roundup(3.4) = 3 + 1 = 4
roundup(3.5) = 4
roundup(3.6) = 4

Yep, correct.

[urraka]

The logic is correct but it doesn't work =/
There is a type mismatch error, I guess you can't compare Extended with Integer, and as I'm not a Pascal (or Delphi?) programmer I don't know how to convert it to match types.

[EnEsCe]

Code: [Select]

strtoint(floattostr(<ExtendedVariableHere>));

[urraka]

This would be the code then:

Code: [Select]

function RoundDown(num:Extended): Integer;
begin
    Result := round(num);
    if StrToFloat(IntToStr(Result)) > num then
        Result := Result - 1;
end;


Code: [Select]

function RoundUp(num:Extended): Integer;
begin
    Result := round(num);
    if StrToFloat(IntToStr(Result)) < num then
        Result := Result + 1;
end;

Float can be compared with Extended i tested it.