I agree completely with #1 ...
--- In [email protected], "Tom Tom" <[EMAIL PROTECTED]> wrote:
>
> Thanks Paul and Ed.
>
> It is a shame because i manage to code AR Burg method all in AFL
native.
> Two points are not so good in my coding :
>
> 1- Loop for need to flip an array. There is no such function in
native AFL,
> but it is very usefull sometimes for many algorythm.
> Exemple : [1 5 4 8] -> [8 4 5 1]
> Is there a way do do it without loop ? (if not possible thomas you
cannot
> add a function flip_array ? very usefull for all lattice filter or
backwards
> recursion)
>
> Code :
> for (j = 1; j < i; j++) a_old_flip[j] = a_old[i-j];
>
> 2- Precision digit make many sensitive algorythm not done by AFL.
Bu i think
> it is done to have full speed from AB, so great.
> But I have not the same result for SUM and FOR(i=0,...)
>
> Code :
>
> AFL SUM function :
> Num = 0; Den = 0;
> Num = Sum(W*f*b_shifted, LongBar - i);
> Den = Sum(W*(f^2 + b_shifted^2), LongBar - i);
> k[i] = 2*Num[LongBar - 1]/Den[LongBar - 1];
>
> FOR :
> Num = 0; Den = 0;
> for (j = i; j < LongBar; j++) {
> Num = Num + 100000*W[j]*( f[j]*b[j-1] );
> Den = Den + 100000*W[j]*( f[j]^2 + b[j-1]^2 );
> }
> k[i] = 2*Num/Den;
>
> I have not the same result for the number k[i] !?
> For small number on small period formula give back same result...
but for
> long periods... i end up with slightly different number (and for
AR coef, it
> means big diff... arhhh).
> which is better SUM or FOR (I had to test by coding it in JSscript
or
> VBscript and compare maybe) ?
>
> Thanks again.
>
> Cheers,
> Mich.
>
>
>
>
> ----- Original Message -----
> From: Ed Hoopes
> To: [email protected]
> Sent: Thursday, November 16, 2006 5:17 PM
> Subject: [amibroker] Re: Digit precision on AB ?
>
>
> Also, the default precision in javascript is double.
>
> --- In [email protected], "Paul Ho" .> wrote:
> >
> >you can only doing single precision floating points within AFL
all
> >functions that I called returned single precision, 1. I thought
it was 8
> >significant digits
> >http://en.wikipedia.org/wiki/IEEE_754;
> >2. yes or dll
> >3. for and sum should give the same answer.
> >cheers
> >Paul.
> >
> >_____
> >
> >From: [email protected] [mailto:[EMAIL PROTECTED]
> On Behalf
> >Of Tom Tom
> >Sent: Thursday, 16 November 2006 7:01 PM
> >To: [email protected]
> >Subject: [amibroker] Digit precision on AB ?
> >
> >
> >
> >Hello,
> >
> >Does someone can help me about digit precision on AB please.
> >
> >1- I think it is 7 signifiant digit +exposant +signe. Am i right ?
> >
> >2- For more precision we need to code in VBscript and enable
double
> float ?
> >
> >3- But if i prefer stay on Amibroker AFL. For a sum loop for
exemple, i
> >didn't have same result with looping with FOR(i=...) and with
> SUM(array,
> >periods). SUM is better ? Native AFL included function work inside
> with only
> >
> >7 digit precision too, or they work in more precision and send
back
> function
> >
> >result in 7 digit format. If it is the case, SUM should give
better
> calcul
> >accuracy than FOR(i=...) ?
> >
> >Thanks,
> >Mich.
> >
> >__________________________________________________________
> >Windows Live Messenger sur i-modeT : dialoguez avec vos amis
depuis
> votre
> >mobile comme sur PC ! http://mobile.
> ><http://mobile.live.fr/messenger/bouygues/>
live.fr/messenger/bouygues/
> >
>
>
>
>
> _________________________________________________________________
> Retrouvez tout en un clin d'oeil avec Live Search !
> http://www.live.com/?mkt=fr-fr
>
