SRL Archive - Discussions and Debates

hey, i looked somewhere earlier where someone had posted a solution to a problem full of "if … or … or … or … or … or … or …" and got curious about how efficient that was.

My conclusion: if or will always check all the cases, no matter if it already found a true one. if not takes a lil longer if the only true case is somewhere towards the end of the list, but is much faster if it is at the beginning. now in this test i only compare booleans, but if we're scanning for colors or something like that it makes a real difference.

Successfully compiled (88 ms)
x = 0
or or or method took 297 ms
if not method took 94 ms
x = 1
or or or method took 296 ms
if not method took 375 ms
Successfully executed

have a good look at why the x is important.

program SmallTest;
var
  RMs: Array[0..8] of Boolean;
  found: boolean;
  i, t, x:integer;
begin
  for x:=0 to 1 do
  begin
    writeln('x = '+IntToStr(x));
      if x=0 then
        RMs[0] := True
      else
        RMs[0] := False;
      RMs[1] := False;
      RMs[2] := False;
      RMs[3] := False;
      RMs[4] := False;
      RMs[5] := False;
      if x=0 then
        RMs[6] := False
      else
        RMs[6] := True;
      RMs[7] := False;
      RMs[8] := False;
      
    t:=GetSystemTime;
    for i:=0 to 10000 do
      if RMs[0] or RMs[1] or RMs[2] or RMs[3] or RMs[4] or RMs[5] or RMs[6] or RMs[7] or RMs[8] then
        Continue;
    writeln('or or or method '+'took '+IntToStr(GetSystemTime-t)+' ms');
    t:= GetSystemTime;
    for i:=0 to 10000 do
    begin
      found:=True;
      if not RMs[0] then
        if not RMs[1] then
          if not RMs[2] then
            if not RMs[3] then
              if not RMs[4] then
                if not RMs[5] then
                  if not RMs[6] then
                    if not RMs[7] then
                      if not RMs[8] then
                        found:=False;
    end;
    writeln('if not method '+'took '+IntToStr(GetSystemTime-t)+' ms');
  end;
end.

and with the if not method we always put those we expect to be the most recurring ones on top.

i was curious about it, and i guess that this might be useful information for some people :)

~RM

That's why I've never bought in to the 'Stepping cases are faster!'… They are, if you expect to fail a lot.

hmm, that's interesting, maybe try xor too and post the result? (i think xor is like "or", but, if its not, then just totally disregard that last statement)

xor is a math function

and are you trying to prove that if not is faster or vice versa, or not at all?:p

Did you try with if not RMs[0] and not RMs[1] etc. as that should exit out when it finds a false value (or true due to the not)?

i think you didn-t see the second part mick, look more closely ;)

   for i:=0 to 10000 do
      if RMs[0] or RMs[1] or RMs[2] or RMs[3] or RMs[4] or RMs[5] or RMs[6] or RMs[7] or RMs[8] then
        Continue;
    writeln('or or or method '+'took '+IntToStr(GetSystemTime-t)+' ms');
    t:= GetSystemTime;
    for i:=0 to 10000 do
    begin
      found:=True;
      if not RMs[0] then
        if not RMs[1] then
          if not RMs[2] then
            if not RMs[3] then
              if not RMs[4] then
                if not RMs[5] then
                  if not RMs[6] then
                    if not RMs[7] then
                      if not RMs[8] then
                        found:=False;
    end;
    writeln('if not method '+'took '+IntToStr(GetSystemTime-t)+' ms');
  end;
end.

drizzt, xor is not what you think it is,

(True xor True) = False
(False xor False) = False
(True xor False) = True
(False xor True) = True

it returns true if they are different. and for maths they work another way.

Dan i was trying to prove if not is faster, but was surprised by the result :p i still believe it'll be faster in most cases because we'll always put the ones with most chance of succeeding first. and i'll try later with color analizes because then it may make a bigger difference even if the one that returns true is one of the last ones to be called.

-RM

Xor, Extensive or, is a logical operator, not a mathematic function, and works as Rasta said. A good example situation is setting run to true for example, or toggling retaliate.

No I mean in one line as it should act the same as that, but I think it may run through all the values anyway if or does too, so I mean literally try:

  if((not(RMs[0])) and (not(RMs[1])) and (not(RMs[2])) and (not(RMs[3])) and (not(RMs[4])) and (not(RMs[5])) and (not(RMs[6])) and (not(RMs[7])) and (not(RMs[8]))) then

:)

mixstrer i think that will will work just like or and lag more because of the "not" but i'll try it once i get home.

and i see you think the same as me but there's no harm in trying :p

~RM

thats why i put it in parenthesis, because i knew i didn't know what i was talking about, but good find rasta

SRL Library Small Tuts about SRL-Functions in here…

Erm…?

From: n3ss3s
Erm…?

find me a better place n ill know next time :) and it is a small tut because we learn in which case a method is faster than the other.

~RM

about SRL-Functions in here…

Or is a logical operator, not an SRL function…

If you see this, read my pm…

Lol?


I bet 'and', the so useful function, and 'not', was also made by Wizzup? and WT-Fakawi!

You think they're that great? Well, you would be right, though their most famous one was repeat until(false) :)