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Hi,
Sometimes things look more complicated than they should :-)
Your formula:
AMA = ref(AMA,-1)+sc*(close-ref(AMA,-1));
Is the same as:
AMA = sc * close + ( 1 - sc ) * Previous( AMA );
This one is in fact the formula for exponential moving average
sc is simply smoothing constant = 2 / (periods + 1)
So periods = -1 + 2/sc
So you final AFL code for your AMA is:
AMA = ema( close, -1 + 2/sc );
It is not only faster to execute but also does not have any self-references.
In AFL you can reference the same variable in the assignment statement
(you must initialize it however):
testvar = 0;
testvar = testvar + close;
But... AFL is a vector (or array) based language performing operations on array
in one run (that's why it is so fast) - so you can not iterate thru elements
of the array. Statements like variable = ref( variable, -1 ) + something
will not work correctly.
To overcome this problem functions like cum(), sum(), ema() should be used.
Best regards,
Tomasz Janeczko
----- Original Message -----
From: <jmjames@xxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Tuesday, March 13, 2001 05:34
Subject: [amibroker] Help with an indicator...
> Hi!
>
> I have had trouble getting an indicator to work. More specific, I
> have had trouble with the following line:
>
> AMA = ref(AMA,-1)+sc*(close-ref(AMA,-1));
>
> It comes back with an error of:
>
> AMA = ref(AMA,
> ^
>
> Unknown identifier
>
> Am I doing something wrong, or will AmiBroker not handel a ref to
> itself?
>
> Thank for your time and effort on my questions!!
>
> Regards,
>
> Jared James
> jjames@xxxx
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
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