OpenEuphoria

Re: Good Use of GOTO

• Posted by jiri babor <jbabor at paradis?.n?t.nz> Jun 06, 2008
• 851 views

Chris Bensler wrote:
> 
> c.k.lester wrote:
> > 
> > Jeremy Cowgar wrote:
> > > c.k.lester wrote:
> > > > How does this compare:
> > > > function factorial_fast(atom a)
> > > > end function
> > > > I show similar improvement vs factorial() without the use of GOTO.
> > > > 
> > > 
> > > I ran it a few times.
> > 
> > So, my factorial_fast() runs in about 1.57s over one million
> > iterations. GOTO runs in about 1.42s for one million iterations.
> > So, the GOTO is about 10% faster, right? In this case, I would
> > use whatever version was in the standard lib. I personally don't have
> > code that iterates one million times, so it wouldn't matter.
> > However, 10% improvement is excellent. Alas, a difference of 0.15
> > seconds is not likely to be noticed by your casual human observer.
> 
> I had jeremy test the following version and he stated that it was 0.006s
> faster
> than the goto version. Admittedly very marginal, but none-the-less, we are
> comparing
> the speed of existing euphoria against gotos in euphoria.
> 
> (Sorry for overstepping you Jeremy, but it would be unfair not to make the
> best
> comparison to something that is being argued as being faster.)
> 
> 
> }}}
<eucode>
> function factorial(atom a)   
>  atom b   
>   b = a   
>    
>   while 1 do
>     if a <= 2 then   
>       exit
>     end if   
>      
>     a = a - 1   
>     b = b * a   
>   end while
>   return b   
> end function 
> </eucode>
{{{

> 
> Maybe this could be made even faster, I'm no speed freak.
> 
> Chris Bensler
> Code is Alchemy


I am no speed freak either, but the following simpler version is at least twice
as fast:

function factorial(atom a)
    atom b

    b = 1
    for i = 2  to a do
        b *= i
    end for
    return b
end function

But that's no argument against goto...

jiri