|
PureBytes Links
Trading Reference Links
|
Tomasz,
Thank you for your reply.
Here is an example:
The
//Code1
for(I=1;I<10^5;I++)
{
X=MA(C,0.001*I);
}
Plot(X,"["+I+"]",colorBlack,1);
needs ~25sec.
The
//Code2
function SMA(PER)
{
return MA(C,0.001*PER);
}
for(I=1;I<10^5;I++)
{
X=SMA(I);
}
Plot(X,"["+I+"]",colorBlack,1);
did not improve the speed.
I do not know *how* could I come to the final result in 5sec, I do
not know how to remove the moving parts from the body of the loop, I
do not know the cost of an if/else statement inside the loop.
So, when I begin thinking of "the closest MA" [a quite interesting
issue...] I need an iteration with MAs and an if statement to apply
the proximity criterion [or a while statement to stop the execution
when the C-SMA is minimum.]
If I come to some 10-15 sec code, it is OK, I can keep on the initial
thought and, probably, come to an interesting result.
If my code needs 2min, I will simply forget all about it and move to
another issue.
Life is short, on the other side, there is no time to study
programming books.
The *only* use, for me, would be the flexibility of my AFL loops, I
do not need programming for other applications.
[Even my weather forecasting formulas are written in AFL !!]
This is why I thought you could write an "AFL looping guide",
whenever of course you decide to use 0.5h from the precious time
devoted to Julia and Jacob !!!
Have a great day !!
Dimitris
--- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <amibroker@xxxx>
wrote:
> Dimitris,
>
> The example was intented to show that implementation of AFL
language contructs
> (like loops) is very, very fast.
> So using loops is not a problem at all.
>
> Problems may start when _the_ _formula_ _you_ _put_ _inside_ the
loop
> is written in inefficient manner.
> I already wrote about some basic techniques like moving invariants
> out of loop plus using variables and calling functions once instead
> of repetitive calling the same functions with same params over and
over again.
> If such inefficient code is wrapped inside several nested loops it
will
> execute slowly no matter in what language is written. Even if you
wrote it
> in assembler (straight machine CPU code)
>
> These are basic things covered in each and every
> book on programming (i.e. they are language-independent, because
> these are 'universal' programing rules not depending on particular
language).
>
> But thank you for your suggestion - I will think about writing some
article
> about good programming practices in next newsletter.
>
> Best regards,
> Tomasz Janeczko
> amibroker.com
> ----- Original Message -----
> From: "DIMITRIS TSOKAKIS" <TSOKAKIS@xxxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Friday, October 01, 2004 8:01 AM
> Subject: [amibroker] Re: NOT REALLY A BUG
>
>
> > Tomasz,
> > Your example is a bit strange. AFL does not need 5sec for 10
million
> > iterations, it is not a global measure, the total time depends
> > strongly on the code. It will not be 5 sec if we use an MA
instead of
> > the sin function, it will be 5min and the total time will be much
> > longer if a Plot statement is added inside the loop.
> > It would help to write some basic "rules" for the execution time
of
> > AFL loops [perhaps in some next newsletter] and some instructions
how
> > to "optimize" AFL loops.
> > Dimitris
> > --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko"
<amibroker@xxxx>
> > wrote:
> >> Hello,
> >>
> >> You should optimize your formula first so it does not ages to
> > execute.
> >>
> >> If your formula takes more than 1 second to execute you probably
> >> did something very weird or wrong because AFL itself including
> > loops are hyper fast.
> >>
> >> For example TEN million iteration of sine function like this:
> >> for(i=0;i<10000000;i++)
> >> {
> >> x = sin(i);
> >> }
> >>
> >> Takes only five seconds, so it takes 0.5 microsecond per
iteration
> > (including calculation
> >> of trigonometric function).
> >>
> >> (Note that if you want to try this code you would need to adjust
> > the endless loop detection
> >> threshold level in Tools->Preferences->AFL to more than 10
million
> > loops, otherwise you will
> >> get endless loop warning).
> >>
> >> Best regards,
> >> Tomasz Janeczko
> >> amibroker.com
> >>
> >> ----- Original Message -----
> >> From: "s.carrasset" <s.carrasset@xxxx>
> >> To: <amibroker@xxxxxxxxxxxxxxx>
> >> Sent: Thursday, September 30, 2004 3:55 PM
> >> Subject: [amibroker] NOT REALLY A BUG
> >>
> >>
> >> > hello, Tomasz.
> >> >
> >> > it can happens ( rarely ^_^) that I get a "displeasure" with
> > amibroker.
> >> > where can I send it , here or support?
> >> > for ex the last one:
> >> >
> >> > if I write or paste a code with many loops (with no error
> > inside) like
> >> > the last one parabolic code of Dimitri in message 71077.
> >> >
> >> > Amibroker becomes very slow to open the symbol workspace even
if
> > i close
> >> > the code's window on the displayed chart pane.
> >> >
> >> > stephane
> >> >
> >> >
> >> >
> >> > 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
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >>
> >> [Non-text portions of this message have been removed]
> >
> >
> >
> >
> > 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
> >
> >
> >
> >
> >
> >
------------------------ Yahoo! Groups Sponsor --------------------~-->
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/GHeqlB/TM
--------------------------------------------------------------------~->
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
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/amibroker/
<*> To unsubscribe from this group, send an email to:
amibroker-unsubscribe@xxxxxxxxxxxxxxx
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
|