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Bill,
If you lookup the AFL reference (http://www.amibroker.com/guide/afl )
you will see that
1. BarIndex() returns the sequential bar number
2. EndValue and BeginValue are universal functions that
allow you to lookup values of the array at the BEGINNING and
the END points of range.
3. WriteVal is really needed only in commentaries. It just converts
the number to string, since only strings (texts) can be outputted in commentary window.
But... In AA window you don't need to use WriteVal at all.
For example in exploration mode you just write
// display only results for last bar of range
Filter = BarIndex() == EndValue( BarIndex() );
Period = EndValue( BarIndex() ) - BeginValue( BarIndex() );
AddColumn( StDev( Close, Period ), "StDev" );
AddColumn( ROC( Close, Period ), "ROC" );
AddColumn( MA( Volume, Period ), "Average Volume" );
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: <wbarack@xxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Sunday, February 16, 2003 7:19 PM
Subject: [amibroker] Re: Number of Days between dates
> Tomasz,
>
> So the thought sequence I need to go through is something like this:
>
> 1. What AFL variable defines the quantity I'm interested in -
> BarIndex().
> 2. What value of that variable do I want - EndValue().
> 3. What do I want to do with that value - WriteVal().
>
> I've go a lot to learn to get my mind wrapped around AFL and the
> language structure.
>
> Thank you for your patience with me.
>
> Bill
>
>
>
> --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <amibroker@xxxx>
> wrote:
> > Bill,
> >
> > One WriteVal() and some braces were missing, corrected one follows:
> >
> > Period = EndValue( BarIndex() ) - BeginValue( BarIndex() )+1;
> >
> > PerChange = WriteVal(100*(EndValue(Close)-BeginValue
> > (Close))/BeginValue(Close));
> >
> > Title ="Percentage change of close is " +
> > PerChange +
> > "%, \nStandard Deviation over the period is " +
> > WriteVal( EndValue( StDev( Close, Period ) ) );
> >
> > BTW: I don't think you need to add +1 to the Period.
> >
> > Best regards,
> > Tomasz Janeczko
> > amibroker.com
> > ----- Original Message -----
> > From: <wbarack@xxxx>
> > To: <amibroker@xxxxxxxxxxxxxxx>
> > Sent: Sunday, February 16, 2003 6:53 PM
> > Subject: [amibroker] Re: Number of Days between dates
> >
> >
> > > Tomasz,
> > >
> > > Well, it didn't take long until I ran into my next roadblock.
> Here is
> > > the code:
> > > -----------
> > > Period = EndValue( BarIndex() ) - BeginValue( BarIndex() )+1;
> > >
> > > PerChange = WriteVal(100*(EndValue(Close)-BeginValue
> > > (Close))/BeginValue(Close));
> > >
> > > Title ="Percentagechange of close is " + PerChange + "%,
> \nStandard
> > > Deviation over the period is "+ EndValue( StDev( Close,
> Period ) ) ;
> > >
> > > ----------------
> > > When I apply it, I get an error indication at the last semicolon
> in
> > > the Title statement.
> > >
> > > Now, another question and this is based on an interpretation of
> the
> > > Period calculation in line 1. Is the appropriate value to use the
> > > difference between the bar indexes or the difference plus 1 to
> use
> > > all the bars in the range. It seems to me that the appropriate on
> > > depends on how the barindex function is constructed.
> > >
> > > Thanks
> > >
> > > Bill
> > > --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko"
> <amibroker@xxxx>
> > > wrote:
> > > > Hello,
> > > >
> > > > I have added the sample codes to:
> > > >
> > > > http://www.amibroker.com/guide/afl/afl_view.php?name=BEGINVALUE
> > > >
> > > > and
> > > >
> > > > http://www.amibroker.com/guide/afl/afl_view.php?name=ENDVALUE
> > > >
> > > >
> > > > Best regards,
> > > > Tomasz Janeczko
> > > > amibroker.com
> > > > ----- Original Message -----
> > > > From: <wbarack@xxxx>
> > > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > > Sent: Sunday, February 16, 2003 5:28 PM
> > > > Subject: [amibroker] Number of Days between dates
> > > >
> > > >
> > > > > I am trying out 4.29.1 and its wonderful new functions that
> let
> > > me
> > > > > select a from-to range on a price plot. Thanks Tomasz. Great
> > > addition.
> > > > >
> > > > > What I want to do is calculate a standard deviation over the
> > > selected
> > > > > range. While the example for "percentage change" in price
> that is
> > > > > included withe download works great, the standard deviation
> > > function,
> > > > > like many others, wants to know the period to be calcated
> over.
> > > > >
> > > > > StDev(array, period);
> > > > >
> > > > > So I am trying to find the period as follows:
> > > > >
> > > > > Range (or period) = EndValue(Datetime())-BeginValues(DateTime
> ());
> > > > >
> > > > > however, this expression and the variants of it that I have
> tried
> > > > > results in error messages when I try to write the value of
> StDev
> > > in a
> > > > > Title expression.
> > > > >
> > > > > I'm sure I messing up formats or something similar and I
> cannot
> > > find
> > > > > the Help descriptions that will get me out of my dilema.
> > > > >
> > > > > Long winded, but the basic question is: "How do I find the
> range
> > > > > in "bars" for a given From-to range such that I can use it in
> > > > > functions like StDev?"
> > > > >
> > > > > Second associated question: "How do I direct the Title
> function
> > > to
> > > > > execute a carriage return?"
> > > > >
> > > > > Thanks
> > > > >
> > > > > Bill
> > > > >
> > > > >
> > > > > Post AmiQuote-related messages ONLY to:
> amiquote@xxxxxxxxxxxxxxx
> > > > > (Web page: http://groups.yahoo.com/group/amiquote/messages/)
> > > > >
> > > > > Check group FAQ at:
> > > http://groups.yahoo.com/group/amibroker/files/groupfaq.html
> > > > >
> > > > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > > > >
> > > > >
> > > > >
> > >
> > >
> > > Post AmiQuote-related messages ONLY to: amiquote@xxxxxxxxxxxxxxx
> > > (Web page: http://groups.yahoo.com/group/amiquote/messages/)
> > >
> > > Check group FAQ at:
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> > >
> > > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
>
>
> Post AmiQuote-related messages ONLY to: amiquote@xxxxxxxxxxxxxxx
> (Web page: http://groups.yahoo.com/group/amiquote/messages/)
>
> Check group FAQ at: http://groups.yahoo.com/group/amibroker/files/groupfaq.html
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
Post AmiQuote-related messages ONLY to: amiquote@xxxxxxxxxxxxxxx
(Web page: http://groups.yahoo.com/group/amiquote/messages/)
Check group FAQ at: http://groups.yahoo.com/group/amibroker/files/groupfaq.html
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