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[amibroker] Re: equivalent of PREV



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Tomasz,

Thanks for your answer. Loops are clearly much more powerfull then MS
PREV.
I think I am still confusing concepts of the different systems I am
looking at at the moment. TradeSignal is all LoopBased (and painfully
slow at that) - the loop is implicit, as the script just gets
evaluated for each bar. MS then is all array or function based. Which
just leaves you with PREV.

I now begin to see that AB is kind of offering best of both worlds
here and gives me the option to choose the most apropriate method myself.

Bests,
~Lars


--- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <amibroker@xxxx>
wrote:
> Hello,
> 
> As I wrote in the past MS PREV is the worst thing they came up with.
> Among other things it is painfully slow (try formula with and
without PREV
> in MS and you will understand what I am talking about - it makes things
> hunderds times slower). 
> They invented PREV because MS is incapable of looping. 
> 
> AmiBroker does not need such pseudo-solutions because you can
> write loops in AFL and easily reference previous values:
> 
> HaOpen = HaClose = (O+H+L+C)/4; 
> 
> for( i = 1; i< BarCount; i++ ) 
> { 
>   HaOpen[ i ] = (HaOpen[ i - 1 ] + HaClose[ i - 1 ]) /2; 
> } 
> 
> Looping has no speed penalty of PREV and it is much more powerful and
> syntactically clearer.
> 
> As for AMA it is actually very easy and powerful way to implement
> any kind of dynamic recursive 1-st order smoothing and there is
nothing odd about it.
> (ask any engineer about 1-st order infinite impulse response filters)
> 
> Best regards,
> Tomasz Janeczko
> amibroker.com
> ----- Original Message ----- 
> From: "Zeno" <lars.oppermann@xxxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Monday, January 10, 2005 11:39 PM
> Subject: [amibroker] Re: equivalent of PREV
> 
> 
> > 
> > 
> > Hermann, Steve,
> > 
> > Thanks so much for your fast reply. My understanding is, that this is
> > 'exploiting' the fact, that AMA is also dependant on a feedback of
> > it's own result. 
> > This is a nice trick, but it strikes my as being somewhat odd :)
> > Shouldn't there be a more elegant way of doing those things in AFL
> > (feature request?)
> > 
> > Thanks again
> > ~Lars
> > 
> > 
> > 
> > 
> > 
> > 
> > Check AmiBroker web page at:
> > http://www.amibroker.com/
> > 
> > Check group FAQ at:
http://groups.yahoo.com/group/amibroker/files/groupfaq.html 
> > Yahoo! Groups Links
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> >





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