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Hello,
About new if-else
if-else statement changes flow of execution (opposite to IIF
function that evaluates all arguments).
and you can not really write
if (H >Ref(H,-1<FONT face=Arial
color=#0000ff size=2>))
because it has no meaning. It would translate to
"If high array is higher than high array shifted
one bar" (see tutorial below)
flow control statement has to get SINGLE boolean
value to make decision which
execution path should be taken.
If you write H (or High) it means ARRAY (entire
array)
if you write H[ i ] - it means i-th element of the
array. The subscript operator [ ]
allows you to access individual array
elements.
Instead you should write:
for( i = 1; i < BarCount; i++ )
{
if ( H[ i ] > H[ i - 1 ] )
x[ i ] = H[ i
];
else
x[ i ] = L[ i
];
}
this will translate to correct one
"for EVERY BAR 'i' assign i-th element of
high array to the i-th element of x array if
i-th element of high array is higher than the previous
element, otherwise assign i-th of
low array to the i-th element of x
array"
As you can see in many cases old-style AFL provides much more
compact
form. I always tried to explain this advantage of AFL but only
a few realised that.
New control statements should be used where it is better to
use them.
As I tried to explain during last years in 80% of cases
'old-style' AFL provides
the shortest formula. Only remaining 20% of cases needed
script.
Those 'script-only' cases now can be coded in native AFL
thanks to new for/while/if-else
statements. And this is correct usage of them - TO REPLACE
SCRIPT PARTS.
Below is a copy of TUTORIAL that explains how array-based
functions (like IIF) work:
Tutorial: Understanding how AFL works
Introduction
One of most important aspects of AFL is that it is an array processing
language. It operates on arrays (or rows/vectors) of data. This way of operation
is quite similar to the way how popular spreadsheets work (like Microsoft
Excel). Anyone familiar with MS Excel should have no trouble quickly picking up
AFL. - In fact all the examples in this article were all created using MS
Excel.
What is an Array?
An array is simply a list (or row) of values. In some books it may be
referred to as a vector. Each numbered row of values in the example represents
an individual array. Amibroker has stored in its database 6 arrays for each
stock. One for opening price, one for the low price, one for the high price, one
for the closing price and one for volume (see the rows labelled 1-5 below) and
one for open interest. These can be referenced in AFL as open, low, high, close,
volume, openint or o, l, h, c, v, oi.
Bar
1
2
3
4
5
6
7
8
9
10
1
Open
1,23
1,24
1,21
1,26
1,24
1,29
1,33
1,32
1,35
1,37
Fig 1. Open price array
Any other array is calculated from these 6 arrays using formulae built into
AFL. These arrays are not stored in the database but calculated where
necessary.
Each individual value in an array has a date associated with it. If you have
the tool tip option turned on (Preferences -> Miscellaneous Tab - > Price
data tool tips), when you move your cursor over candle on a daily candle chart,
a small yellow rectangle appears. AFL then looks up the open, low, high, close,
volume values in the appropriate array and displays them inside the tool tip.
Processing arrays - why is AFL so fast?
Lets see how the following statement is processed:
MyVariable = ( High + Low )/2;
When AFL is evaluating statement like this ( High + Low )/2 it does not need
to re-interpret this code for each bar. Instead it takes the High ARRAY and Low
ARRAY and adds corresponding array elements in single stage. In other words +
operator (and other operators too) work on arrays at once and it is executed at
full compiled-code speed, then the resulting array (each element of it) is
divided by 2 also in single stage.
Let's look into the details - see fig 2.. When AFL engine looks at the ( High
+ Low )/2 it first takes High (1) and Low (2) arrays and produces (in single
compiled step) the temporary array (3). Then it creates the final array (4) by
dividing each element of temporary array by two. This result is assigned to
myVariable
Bar
1
2
3
4
5
6
7
8
9
10
1
High (built-in array)
1,24
1,27
1,25
1,29
1,25
1,29
1,35
1,35
1,37
1,29
2
Low (built-in array)
1,20
1,21
1,19
1,20
1,21
1,24
1,30
1,28
1,31
1,27
3
High+Low (temporary array created during
evaluation)
2,44
2,48
2,44
2,49
2,46
2,53
2,65
2,63
2,68
2,46
4
( High+Low ) /2 (gets assigned to MyVariable)
1,22
1,24
1,22
1,245
1,23
1,265
1,325
1,315
1,34
1,23
Fig 2. AFL steps when processing ( High + Low ) /2
Moving averages, conditional statements
Let us now consider the following code:
Cond1 = Close > MA( Close, 3 );Cond2 = Volume > Ref( Volume,
-1 );Buy = Cond1 AND Cond2;Sell = High > 1.30;
This code generates a buy signal when todays close is higher than 3 day
moving average of close AND todays volume is higher than yesterday's volume. It
also generates a sell signal when today's high is higher than 1.30.
If in your AFL code you need to see if the closing price is greater than say
a 3 day simple moving average AFL will first run through the close array
creating a new array called MA(close,3) for the stock being analysed. Each cell
in the new array can then be compared one for one in the close array. In the
example an array called Cond1 is created this way. For each cell where the
closing price is greater than the corresponding cell value in MA(close,3) the
cell value for new array 'Cond1' is set to '1'. If the closing price is not
greater than the corresponding price in the close array the value in 'Cond1' is
set to '0'.
AFL can also look forwards or backwards a number of cells in an array using
the Ref function (see row 6 where temporary array is created
holding previous day volume)
In row 9 a new array called Cond2 has been created by comparing the value of
each cell in the volume array with its previous cell setting the Cond2 cell
value to '1' if true and '0' if false.
Row 10 shows an array called 'Buy' created by comparing the cell values in
Cond1 with the cell values in Cond2. If the cell in Cond1 has a '1' AND so does
the corresponding cell in Cond2 then a '1' is placed in the 'Buy' array
cell.
Row 11 shows an array called 'Sell' created whenever the cell value in the
close array is greater than $1.30.
Day
1
2
3
4
5
6
7
8
9
10
1
Open
1,23
1,24
1,21
1,26
1,24
1,29
1,33
1,32
1,35
1,37
2
High
1,24
1,27
1,25
1,29
1,25
1,29
1,35
1,35
1,37
1,29
3
Low
1,20
1,21
1,19
1,20
1,21
1,24
1,30
1,28
1,31
1,27
4
Close
1,23
1,26
1,24
1,28
1,25
1,25
1,31
1,30
1,32
1,28
5
Volume
8310
3021
5325
2834
1432
5666
7847
555
6749
3456
6
Ref( Volume, -1 ) (temporary
array created during eval)
Null
8310
3021
5325
2834
1432
5666
7847
555
6749
7
MA( Close, 3 ) (temporary array created
during eval)
Null
Null
1,243
1,260
1,257
1,260
1,270
1,287
1,310
1,300
8
Cond1 = Close > MA(close,3) (gives 1 (or true) if
condition met, zero otherwise)
Null
Null
1
0
1
1
0
0
0
1
9
Cond2 = Volume > Ref(volume,-1)
Null
0
1
0
0
1
1
0
1
0
10
Buy = Cond1 AND Cond2
Null
Null
1
0
0
1
0
0
0
0
11
Sell = High > 1.30
0
0
0
0
0
0
1
1
1
0
Obviously Buy and Sell are special arrays whose results can be displayed in
the Analyser window or on screen using a red or green value as needed.
Getting little bit more complex
The examples above were very simple. Now I will just explain 3 things that
seem to generate some confusion among the users:
referencing selected values (SelectedValue, BeginValue, EndValue,
LastValue)
IIF function
AMA function
As written in the <A
href="">Tutorial:
Basic charting guide you can select any quote from the chart and you can
mark From-To range. The bar selected by verticall line is called "selected" bar
while start and end bars of the range are called "begin" and "end" bars. AFL has
special functions that allow to reference value of the array at selected, begin
and end bar respectively. These functions are called SelectedValue, BeginValue
and EndValue. There is one more function called LastValue that allows to get the
value of the array at the very last bar. These four functions take the array
element at given bar and return SINGLE NUMBER representing the value of the
array at given point. This allows to calculate some statistics regarding
selected points. For example:
EndValue( Close ) - BeginValue( Close )
Will give you dollar change between close prices in selected from-to
range.
When number retrieved by any of these functions is compared to an array or
any other arithmetic operation involving number and the array is performed it
works like the number spanned all array elements. This is illustrated in the
table below (rows 2, 6, 7). Green color marks "begin" bar and red color marks
"end" bar. Selected bar is marked with blue.
Day
1
2
3
4
5
6
7
8
9
10
1
Open
1,23
1,24
1,21
1,26
1,24
1,29
1,33
1,32
1,35
1,37
2
BeginValue( Open )
1,24
1,24
1,24
1,24
1,24
1,24
1,24
1,24
1,24
1,24
3
EndValue( Open )
1,32
1,32
1,32
1,32
1,32
1,32
1,32
1,32
1,32
1,32
4
SelectedValue( Open )
1,21
1,21
1,21
1,21
1,21
1,21
1,21
1,21
1,21
1,21
5
LastValue( Open )
1,37
1,37
1,37
1,37
1,37
1,37
1,37
1,37
1,37
1,37
6
Close
1,22
1,26
1,23
1,28
1,25
1,25
1,31
1,30
1,32
1,28
7
Close <= BeginValue( Open )
1
0
1
0
0
0
0
0
0
0
8
result = IIF( Close <= BeginValue( Open ), Close, Open );
1,22
1,24
1,23
1,26
1,24
1,29
1,33
1,32
1,35
1,37
9
Period
2
3
4
2
3
5
2
3
4
2
10
Factor = 2/(Period+1)
0,667
0,500
0,400
0,667
0,500
0,333
0,667
0,500
0,400
0,667
11
1 - Factor
0,333
0,500
0,600
0,333
0,500
0,667
0,333
0,500
0,600
0,333
12
AMA( Close, Factor )
0,8125
1,0363
1,1138
1,2234
1,2367
1,2399
1,2853
1,2927
1,3036
1,2866
Now the <A
href="">IIF(condition,
truepart, falsepart) function. It works that it returns the value of second
(truepart) or third (falsepart) argument depending on
condition. As you can see in the table above in row 8 the values come
from Close array (truepart) for bars when condition is true (1) and come
from Open array (falsepart) for the remaining bars. In that case the
array returned by IIF function consists of some values from Close and some
values from Open array. Note that both truepart and falsepart are
arrays and they are evaluated regardless of the condition (so this is not a
regular IF-THEN-ELSE statement but function that returns array)
The <A
href="">AMA(
array, factor) function seems to cause the most problems with understanding
it. But in fact it is very simple. It works in recursive way. It means that it
uses its previous value for the calculation of current value. It processes array
bar by bar, with each step it multiplies given cell of first argument (array) by
given cell of second argument (factor) and adds it to the previous value of AMA
multiplied by (1-factor). Lets consider column 3. The value of AMA in the column
3 is given by multipling close price from column 3 (<FONT
color=#cc00cc>1,23) by factor (0,4). Than we add the previous value of
AMA (1,0363) multiplied by (1-factor = 0,6). The
result (rounded to 4 places) is 1,23 * 0,4 + 1,0363 * 0,6 = 1,1138.
If you look at the figures in the row 12 you may notice that these values
look like a moving average of close. And that's true. We actually presented how
to calculate variable-period exponential moving average using AMA function.
If you're having trouble coding AFL I suggest you generate the arrays in the
example in Excel for yourself. If that's a problem get some help from a friend -
especially if that friend is an accountant.
Once you've got the hang of it you can code any system from a book on trading
- or build one yourself.
Best regards,Tomasz Janeczkoamibroker.com
<BLOCKQUOTE
>
----- Original Message -----
<DIV
>From:
<A title=jcasavant@xxxxxxxxxxxx
href="">Jayson
To: <A title=amibroker@xxxxxxxxxxxxxxx
href="">amibroker@xxxxxxxxxxxxxxx
Sent: Wednesday, April 16, 2003 7:26
PM
Subject: RE: [amibroker] AmiBroker 4.31.0
BETA Examples
<SPAN
class=586003616-16042003>Anyone,
<SPAN
class=586003616-16042003>
Ok,
a very simple example.....
<SPAN
class=586003616-16042003> <FONT
size=2>
x=IIf
(H
>Ref(<FONT
color=#000000>H,-<FONT
color=#ff00ff>1)<FONT
color=#282828>,H<FONT
color=#282828>,L<FONT
color=#282828>); this would result
in a line touching either the h or low of each bar based on the
condition.<SPAN
class=586003616-16042003><FONT
size=2>
if (H >Ref(H,-1<FONT
face=Arial color=#0000ff size=2>))<FONT
face=Arial>
y = H<FONT face=Arial
color=#0000ff>;
<FONT face=Arial color=#0000ff
size=2>else
y =L;<FONT
color=#0000ff>
Plot(y,<FONT
color=#ff00ff>"HL",<FONT
color=#000000>colorYellow<FONT
size=2>,1<FONT
color=#282828>);<FONT
color=#0000ff>
Plot(<FONT
color=#000000>C<FONT
color=#282828>,""<FONT
color=#282828>,4<FONT
color=#282828>,<FONT
color=#000000>styleCandle<FONT
face=Arial size=2>);
<SPAN
class=586003616-16042003>rather than evaluating the condition on a bar by bar
basis this looks to lastvalue(h) to determine Y for the whole chart. How would
I use the if/else syntax to copy IFF?
Jayson
<FONT face=Tahoma
size=2>-----Original Message-----From: bluesinvestor
[mailto:investor@xxxxxxxxxxxxx]Sent: Wednesday, April 16, 2003
11:00 AMTo: amibroker@xxxxxxxxxxxxxxxSubject: RE:
[amibroker] AmiBroker 4.31.0 BETA Examples
<SPAN
>Actually let me
clarify something:
<FONT face="Arial CE" color=blue
size=2><SPAN
>condition<FONT
face="Arial CE" color=blue size=2><SPAN
> expression=
i<<SPAN
class=SpellE>barcount;
<FONT face="Arial CE" color=blue
size=2><SPAN
>means do the
loop as long as i< the current <SPAN
class=SpellE>barcount (like cum(1))??
<SPAN
>YES<FONT
face="Courier New" size=2><SPAN
>
<SPAN
>this<FONT
face=Arial color=navy size=2><SPAN
> would actually be
something like do the loop as long as i<<SPAN
class=SpellE>barcount where barcount = <SPAN
class=SpellE>lastvalue(cum(1))
<SPAN
>
<SPAN
>Regards,
<SPAN
>Peter
<SPAN
>
<SPAN
>-----Original
Message-----From:
bluesinvestor [mailto:investor@xxxxxxxxxxxxx] <SPAN
>Sent: <st1:date Month="4"
Day="16" Year="2003"><SPAN
>Wednesday, April 16,
2003<SPAN
> <st1:time
Hour="10" Minute="51"><SPAN
>10:51
AM<SPAN
><SPAN
>To: amibroker@xxxxxxxxxxxxxxx<SPAN
>Subject: RE: [amibroker] AmiBroker 4.31.0
BETA Examples
<FONT face="Times New Roman"
size=3>
<FONT face=Arial color=navy
size=2>Hello
Jayson,
<FONT face=Arial color=navy
size=2><SPAN
>
<FONT face=Arial
color=blue size=2><SPAN
>myema[ 0 ] = close
[0];<SPAN
>
<FONT face=Arial color=navy
size=2><SPAN
>
<FONT face=Arial color=navy
size=2><SPAN
>Amibroker uses zero
based arrays meaning that the first record in an array is at the 0
position. Basically this just
gives a value to the first myema array.
The zero position is the first data record of the close
array.
<FONT face=Arial color=navy
size=2><SPAN
>
<FONT face="Arial CE" color=blue
size=2><SPAN
>for
(<SPAN
> <SPAN
>init-expression <SPAN
>; <SPAN
>cond-expression <SPAN
>; <SPAN
>loop-expression <SPAN
>) <SPAN
>statement <FONT
face="Courier New" size=2><SPAN
>
<FONT face="Arial CE"
color=blue size=2><SPAN
>init-expression=
i=1;
<FONT face="Arial CE" color=blue
size=2><SPAN
>means we start
the loop with i=1? <FONT face="Arial CE"
color=red size=2><SPAN
>YES<FONT
face="Courier New" size=2><SPAN
>
<FONT face="Arial CE"
color=blue size=2><SPAN
>condition
expression= i<barcount;
<FONT face="Arial CE" color=blue
size=2><SPAN
>means do the
loop as long as i< the current barcount (like cum(1))??
<SPAN
>YES<FONT
face="Courier New" size=2><SPAN
>
<FONT face="Arial CE"
color=blue size=2><SPAN
>loop expression=
i<SPAN
>++
<FONT face="Arial CE" color=blue
size=2><SPAN
>means
i+i+i ??????????<SPAN
> <FONT face="Arial CE" color=red
size=2><SPAN
>basically this
just means i = i + 1<FONT face="Arial CE"
color=red><SPAN
>
<FONT face="Arial CE"
color=red size=2><SPAN
>
<FONT face=Arial color=navy
size=2>Hope
this helps,<SPAN
>
<FONT face=Arial color=navy
size=2><SPAN
>Peter
<SPAN
>
<SPAN
>-----Original
Message-----From: Jayson
[mailto:jcasavant@xxxxxxxxxxxx] <SPAN
>Sent: <st1:date Month="4"
Day="16" Year="2003"><SPAN
>Wednesday, April 16,
2003<SPAN
> <st1:time
Hour="10" Minute="35"><SPAN
>10:35
AM<SPAN
><SPAN
>To: amibroker@xxxxxxxxxxxxxxx<SPAN
>Subject: RE: [amibroker] AmiBroker 4.31.0
BETA Examples
<FONT face="Times New Roman"
size=3>
<FONT face=Arial color=blue
size=2>"All you
really need to know about new features in AFL<FONT face=Arial
color=blue>
<FONT face=Arial color=blue
size=2>I
described in:<SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
> <FONT
face=Arial color=blue><SPAN
>
<FONT face=Arial color=blue
size=3><A
href=""><FONT
size=2><SPAN
>http://groups.yahoo.com/group/amibroker/message/37591<FONT
face=Arial color=blue size=2><SPAN
>
"<SPAN
>
<FONT face=Arial color=blue
size=3><SPAN
>
<FONT face=Arial color=blue
size=3><SPAN
>
<FONT face=Arial color=blue
size=2>Well,
almost all........ <SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
>
<FONT face=Arial color=blue
size=2>Tomasz
or any one smarter than me,
<FONT face="Times New Roman"
size=3>
<FONT face=Arial color=blue
size=2>Examples
certainly help. But I am still a bit lost.... from the
post....
<FONT face="Times New Roman"
size=3>
<SPAN
>
<FONT face=Arial color=red
size=2>This
example illustrates the for
statement: <SPAN
><FONT
face=Arial color=red size=2><SPAN
> <FONT
face="Courier New" size=2><SPAN
>
<FONT face="Courier New"
color=red size=2>myema[ 0 ] = Close[
0 ];
<FONT face=Arial color=red
size=2>for( i =
1; i < BarCount; i++ )<FONT face=Arial color=red
size=2><SPAN
><FONT
face=Arial><SPAN
>{<FONT
face=Arial>myema[ i ] = 0.1 * Close[ i ] +
0.9 * myema[ i - 1 ];<FONT
face="Courier New" size=2><SPAN
>
<FONT face="Courier New"
size=2><SPAN
>
<FONT face=Arial color=blue
size=2>myema[ 0
] = close [0];<SPAN
>
<FONT face="Courier New"
size=2><SPAN
>
<FONT face=Arial color=blue
size=2>Do I
assume this translates to..... myema today =close
today ?? similar to myema=c;??<FONT
face="Courier New" size=2><SPAN
>
<FONT face="Courier New"
size=2><SPAN
>
<FONT face="Arial CE" color=blue
size=2><SPAN
>for
(<SPAN
> <SPAN
>init-expression <SPAN
>; <SPAN
>cond-expression <SPAN
>; <SPAN
>loop-expression <SPAN
>) <SPAN
>statement <FONT
face="Courier New" size=2><SPAN
>
<FONT face="Arial CE"
color=blue size=2><SPAN
>init-expression=
i=1;
<FONT face="Arial CE" color=blue
size=2><SPAN
>means we start
the loop with i=1?<SPAN
>
<FONT face="Arial CE"
color=blue size=2><SPAN
>condition
expression= i<barcount;
<FONT face="Arial CE" color=blue
size=2><SPAN
>means do the
loop as long as i< the current barcount (like
cum(1))??<SPAN
>
<FONT face="Arial CE"
color=blue size=2><SPAN
>loop expression=
i++ <FONT face="Arial CE"
color=blue size=2><SPAN
>means
i+i+i ??????????<SPAN
>
<FONT face=Arial color=blue
size=2>Could
someone please convert the expression to
english? <SPAN
>
<FONT face="Courier New"
size=2><SPAN
>
<FONT face="Arial CE" color=blue
size=2><SPAN
>Tia,<FONT
face="Courier New" size=2><SPAN
>
<FONT face="Times New Roman"
size=3>
<FONT face=Arial color=blue
size=2>Jayson
<P class=MsoNormal
><FONT
face=Tahoma size=2><SPAN
>-----Original
Message-----From: Tomasz
Janeczko [mailto:amibroker@xxxxxx]<SPAN
>Sent: <st1:date Month="4"
Day="16" Year="2003"><SPAN
>Wednesday, April 16,
2003<SPAN
> <st1:time Hour="5"
Minute="53"><SPAN
>5:53
AM<SPAN
><SPAN
>To: amibroker@xxxxxxxxxxxxxxx<SPAN
>Subject: Re: [amibroker] AmiBroker 4.31.0
BETA Examples
<FONT face="Times New Roman"
size=2>Hello,
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=2>I fully agree. for/while/if-else + array
access is covered
<FONT face="Times New Roman"
size=2>on 3 or 4 pages of any C/C++
book
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=2>So this is actually less than 1% of
entire C/C++ book.
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=2>So there is absolutely no need to
buy/read C++ book
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=2>All you really need to know about new
features in AFL
<FONT face="Times New Roman"
size=2>I described
in:
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=2><A
href="">http://groups.yahoo.com/group/amibroker/message/37591
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=3>
<FONT face="Times New Roman"
size=3>Best regards,Tomasz
Janeczkoamibroker.com
<BLOCKQUOTE
>
<SPAN
>----- Original Message -----
<FONT
face=Arial size=2><SPAN
>From:<FONT
face=Arial size=2> <A
title=uenal.mutlu@xxxxxxxxxxx
href="">uenal.mutlu@xxxxxxxxxxx
<SPAN
>To:<FONT
face=Arial size=2> <A
title=amibroker@xxxxxxxxxxxxxxx
href="">amibroker@xxxxxxxxxxxxxxx
<SPAN
>Sent:<FONT
face=Arial size=2>
<FONT face=Arial
size=2>Wednesday, April
16, 2003<SPAN
> <st1:time
Hour="10" Minute="39"><SPAN
>10:39
AM<SPAN
>
<SPAN
>Subject:<FONT
face=Arial size=2> Re:
[amibroker] AmiBroker 4.31.0 BETA
Examples
<FONT face="Times New Roman"
size=3><SPAN
>
<SPAN
>Hi
Steve,
<SPAN
>C++ is definitely not
required to program in AFL;
<SPAN
>it would be an overkill!
C++ covers maybe 10 times
<SPAN
>more stuff than
AFL.
<SPAN
>The new stuff in AFL is easily
learnt within 2 hours.
<SPAN
>Simply ask the people here.
<SPAN
>UM
<FONT face="Times New Roman"
size=3><SPAN
>
<BLOCKQUOTE
>
<SPAN
>----- Original Message -----
<FONT
face=Arial size=2><SPAN
>From:<FONT
face=Arial size=2> <A
title=jcasavant@xxxxxxxxxxxx
href="">Jayson
<FONT face=Arial
size=2><SPAN
>To:<FONT
face=Arial size=2> <A
title=amibroker@xxxxxxxxxxxxxxx
href="">amibroker@xxxxxxxxxxxxxxx
<FONT face=Arial
size=2><SPAN
>Sent:<FONT
face=Arial size=2>
<FONT face=Arial
size=2>Wednesday, April
16, 2003<SPAN
> <st1:time
Hour="6" Minute="50"><SPAN
>6:50
AM<SPAN
>
<FONT face=Arial
size=2><SPAN
>Subject:<FONT
face=Arial size=2> RE:
[amibroker] AmiBroker 4.31.0 BETA
Examples
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
>Thank you Steve,
I will see if I can locate a copy.
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
>Regards,
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
>Jayson
<P class=MsoNormal
><FONT
face=Tahoma size=2><SPAN
>-----Original
Message-----From: Steve
Dugas [mailto:sjdugas@xxxxxxxxx]<SPAN
>Sent: <st1:date
Month="4" Day="15" Year="2003"><SPAN
>Tuesday, April 15,
2003<SPAN
> <st1:time
Hour="23" Minute="22"><SPAN
>11:22
PM<SPAN
><SPAN
>To: <A
href="">amibroker@xxxxxxxxxxxxxxx<SPAN
>Subject: Re: [amibroker] AmiBroker
4.31.0 BETA Examples
<FONT face="Times New Roman"
size=2>Hi
Jayson,
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>Sorry to offer the help and then not
be around to follow through on it. But, Monday seems to roll around almost
every week these days, and then its off to work again. Better for you
though - TJ filled in for me : -
)
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>I'm not sure what kind of book you
would like, but since TJ seems to follow C++ syntax, I can recommend a C++
book that I found to be very good (pretty big though - over 1000 pages).
It is very thorough and easy to understand - definitely geared for
beginners in my opinion. It is "C++ Primer Plus" by Stephen Prata. I think
you could probably just read up on the items you are interested in if you
aren't interested in learning the whole language. Be careful because it
seems that there are a couple of other C++ books that call themselves
"primers", but are definitely NOT for beginners. Especially stay away
from Stanley Lippman's book, at least until you have some experience (take
it from me....please!).
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2><SPAN
>Steve
<FONT face="Times New Roman"
size=3><SPAN
>
<BLOCKQUOTE
>
<FONT face=Arial
size=2>----- Original
Message -----
<P class=MsoNormal
><FONT face=Arial
size=2><SPAN
>From:<FONT
face=Arial size=2> <A
title=jcasavant@xxxxxxxxxxxx
href="">Jayson
<FONT face=Arial
size=2><SPAN
>To:<FONT
face=Arial size=2> <A
title=amibroker@xxxxxxxxxxxxxxx
href="">amibroker@xxxxxxxxxxxxxxx
<FONT face=Arial
size=2><SPAN
>Sent:<FONT
face=Arial size=2>
<FONT face=Arial
size=2>Monday, April
14, 2003<SPAN
> <st1:time
Hour="10" Minute="1"><SPAN
>10:01
AM<SPAN
>
<FONT face=Arial
size=2><SPAN
>Subject:<FONT
face=Arial size=2> RE:
[amibroker] AmiBroker 4.31.0 BETA
Examples
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
>Thank you
Tomasz. I have obviously gone from being fairly high on the learning
curve to Newbie in just one week end
:(
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
>Could you
recommend a beginner level book that may help some of us get up to speed
with this new upgrade? I might as well be reading Japanese , but I don't
want to start THAT thread again :))
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face=Arial color=blue
size=2><SPAN
>Jayson
<P class=MsoNormal
><FONT
face=Tahoma size=2><SPAN
>-----Original
Message-----From:
Tomasz Janeczko [mailto:amibroker@xxxxxx]<SPAN
>Sent: <st1:date
Month="4" Day="14" Year="2003"><SPAN
>Monday, April 14,
2003<SPAN
> <st1:time
Hour="3" Minute="54"><SPAN
>3:54
AM<SPAN
><SPAN
>To:
amibroker@xxxxxxxxxxxxxxx<SPAN
>Subject: Re: [amibroker] AmiBroker
4.31.0 BETA Examples
<FONT face="Times New Roman"
size=2><SPAN
>Hello,
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>While IIF works on
ARRAY,
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>if/else works on INDIVIDUAL
number/boolean (element of the
array).
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>Therefore you should write
either
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>a1 = IIF( C > Ref( C, -1 ), 1, 0
);
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>(or even: a1 = C > Ref( C, -1
);
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>or
iterate:
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>for( i = 1; i < BarCount; i++
)
<FONT face="Times New Roman"
size=2><SPAN
>{
<FONT face="Times New Roman"
size=2> if ( Close[ i ]
> Close[ i - 1 ] )
<FONT face="Times New Roman"
size=2><SPAN
> a1[ i ] =
1;
<FONT face="Times New Roman"
size=2>
else
<FONT face="Times New Roman"
size=2><SPAN
> a1[ i
] = 0;
<FONT face="Times New Roman"
size=2><SPAN
>}
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>It is important to understand that
IIF is a FUNCTION that works on
arrays,
<FONT face="Times New Roman"
size=2>while if/else is control flow
STATEMENT.
<FONT face="Times New Roman"
size=2>Function just evaluates all
arguments and returns value(s)
<FONT face="Times New Roman"
size=2>Control flow statement changes
program flow.
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=2>This is fundamental
difference.
<FONT face="Times New Roman"
size=3><SPAN
>
<FONT face="Times New Roman"
size=3>Best regards,Tomasz
Janeczkoamibroker.com
<BLOCKQUOTE
>
<FONT face=Arial
size=2>-----
Original Message -----
<P class=MsoNormal
><FONT face=Arial
size=2><SPAN
>From:<FONT
face=Arial size=2>
<A title=jcasavant@xxxxxxxxxxxx
href="">Jayson
<FONT face=Arial
size=2><SPAN
>To:<FONT
face=Arial size=2>
<A title=amibroker@xxxxxxxxxxxxxxx
href="">amibroker@xxxxxxxxxxxxxxx
<FONT face=Arial
size=2><SPAN
>Sent:<FONT
face=Arial size=2>
Monday, April 14, 2003 7:55 AM
<FONT face=Arial
size=2><SPAN
>Subject:<FONT
face=Arial size=2>
RE: [amibroker] AmiBroker 4.31.0 BETA
Examples
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT face=Arial
color=blue size=2><SPAN
>Steve,
<FONT face=Arial
color=blue size=2><SPAN
>Your example
makes sense yet does not seem to work for me. Else seems to be ignored
. Using the IIF this would simply be
......
<FONT face=Arial
color=blue size=2><SPAN
>a1=iif(c>ref(c,-1),1,0);
I am certainly missing something here.... your input
appreciated..
<FONT face=Arial
color=blue size=2><SPAN
>jayson
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT face=Arial
color=blue size=2><SPAN
><IMG
id=_x0000_i1025 height=638 src="gif00226.gif"
width=752 align=baseline border=0>
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT face=Arial
color=blue size=2><SPAN
>Jayson
<P class=MsoNormal
><FONT
face=Tahoma size=2><SPAN
>-----Original
Message-----From:
Steve Dugas [mailto:sjdugas@xxxxxxxxx]<SPAN
>Sent: Sunday, April 13, 2003
11:25 AMTo:
amibroker@xxxxxxxxxxxxxxx<SPAN
>Subject: Re: [amibroker]
AmiBroker 4.31.0 BETA Examples
<FONT
face="Times New Roman" size=2>Hi
Ken,
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2>I think
the concept of loops and if-then-else is the same in all languages. I
imagine you could read up on it at many websites (e.g.
- MSDN scripting site). Once you grasp the concept, it is just a
matter of using AFL syntax. You would probably use it mostly for
iterating your arrays if you wanted to do that. Here is a simple
pseudo-code - try coding it in AFL:
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2>For
(SecondBar to LastBar)
<FONT
face="Times New Roman" size=2> If
(Today's Close > Yesterday's
Close)
<FONT
face="Times New Roman" size=2><SPAN
> MyArray =
1
<FONT
face="Times New Roman" size=2>
Else
<FONT
face="Times New Roman" size=2><SPAN
> MyArray =
0
<FONT
face="Times New Roman" size=2>Plot
MyArray
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2>Of course,
please feel free to ask for help!
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2><SPAN
>Steve
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=3>-----
Original Message -----
<BLOCKQUOTE
>
<P class=MsoNormal
><FONT face=Arial
size=2><SPAN
>From:<FONT
face=Arial size=2>
Tomasz
Janeczko
<FONT face=Arial
size=2><SPAN
>To:<FONT
face=Arial size=2>
<A title=amibroker@xxxxxxxxxxxxxxx
href="">amibroker@xxxxxxxxxxxxxxx
<FONT face=Arial
size=2><SPAN
>Sent:<FONT
face=Arial size=2>
Sunday, April 13, 2003 10:39 AM
<FONT face=Arial
size=2><SPAN
>Subject:<FONT
face=Arial size=2>
Re: [amibroker] AmiBroker 4.31.0 BETA
Examples
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2><SPAN
>Ken,
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2>Very
nice story :-)
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2>As per
your request, attached is a Parabolic SAR formula
<FONT
face="Times New Roman" size=2>that I
have rewritten from JScript
version
<FONT
face="Times New Roman" size=2><SPAN
>(<A
href=""><FONT
size=2><SPAN
>http://www.amibroker.com/library/detail.php?id=242<FONT
size=2><SPAN
>)
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2>Best
regards,Tomasz
Janeczkoamibroker.com
<FONT
face="Times New Roman" size=2>-----
Original Message -----
<FONT
face="Times New Roman" size=2>From:
"Ken Close" <<A
href=""><SPAN
>closeks@xxxxxxxx<FONT
size=2><SPAN
>>
<FONT
face="Times New Roman" size=2>To:
<<FONT
size=2><SPAN
>amibroker@xxxxxxxxxxxxxxx<FONT
size=2><SPAN
>>
<FONT
face="Times New Roman" size=2>Sent:
Sunday, April 13, 2003 4:05 PM
<FONT
face="Times New Roman" size=2>Subject:
RE: [amibroker] AmiBroker 4.31.0 BETA
Examples
<FONT
face="Times New Roman" size=3><SPAN
>
<FONT
face="Times New Roman" size=2>>
Tomasz:> > As always, you have good sound
advice. However......> > You say, "Here is a
fast sports car, very versatile and powerful. It> has 7
forward gears, but if you are a beginner, do not
worry....always> stay in maximum of 4th gear. Plenty of nice
driving is possible in 4th> gear. Wait until you
become more experienced before you try gears 5,> 6, and
7."> > I say, "Thank you for providing such a nimble
sports car, but I am in a> race, and I do not think I can
finish even 10th in this race, until I> get out past 4th
gear. If you or others would just provide some more>
examples of how to use 5th and 6th gear, then I could more
confidently> try them. Maybe even copy your use of them.
Then, probably, I will have> enough experience to try 7th
gear on my own."> > More examples is all I am asking
for....my objective is not to stay in> 4th gear.>
> Thanks,> > Ken> > -----Original
Message-----> From: Tomasz Janeczko [mailto:amibroker@xxxxxx]
> Sent: Sunday, April 13, 2003 9:47 AM> To:
<FONT
size=2><SPAN
>amibroker@xxxxxxxxxxxxxxx<FONT
size=2>> Subject: Re: [amibroker]
AmiBroker 4.31.0 BETA Examples> > Ken,>
> > First, additional kudos to Tomasz for another
step-jump in capability> of> > Amibroker.>
Thank you.> > > Second, a caution, in marketing
terms, of having capability that is so> > hard to apply
for "non-programmers", beginners, and non-technical>
types> > that the extra capability is viewed not as an
advantage or benefit,> but> > just the
opposite.> > The beginners don't really need to jump
into deep water right from> the start as AFL still supports
"old-way" of work.> > When you write> >
TypicalPrice = (H+L+C) /3;> > it still operates on H,
L, C arrays and produces array so no> looping is
needed.> > New features are added as 'extra' stuff and
do not> change the way old statements work.> >
> I apologize - but may speak for many hidden lurkers - that I
have just> > mastered the idea that "every AFL statement
only executes once", but> now> > I must scramble to
reorient my brain for repeated iterations thru AFL> >
statements.> > See above - you don't need really to
write loops if you don't want them.> All previously written
code will execute the same way as before.> > Unless
you use a while and/or for loop nothing has really changed.>
> So, you don't really need to "re-orient your brain"
:-)> > You can view new features as a replacement of
JScript/VBScript.> You may use these new features only when
you needed to use> scripting in previous versions.>
> Best regards,> Tomasz Janeczko>
amibroker.com
<FONT face="Times New Roman"
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