[amibroker] AFL for Dummies

["matrix10014" <allansn@xxxxxxxxxxxxx>]

Hi all,
Very new to Ami,and so far so good...Its a great program with a 
great users group.I would like to know if I am the only one out 
there who would deeply appreciate an "AFL coding manual for 
Dummies"??.As far as I can tell,the only written explainations are 
on pg 284-307 of the users manual.

I bring this up as I was attempting to code a simple system that
backtests a list of Zacks fundamentally backtested stocks that I 
import into a watchlist.

   
The simple test was as automatic long position..(Buy=1;)
1)I wanted to have a 8% maximum stop.
2)What i wanted to then do is sell 50% of my position up 20%(profit 
target)
3)On the remaining 50%,I wanted to move my 8% maximum stop 
to "breakeven",or perhaps an 50% trailing stop on the open 50% 
position..

I did find a code in the users manual(shown below) which had  
similar conditions.The buy filter in the example was a moving 
average cross which i changed,and there were 2 profit targets as 
well as an initial trailing stop.I am assuming my simpler example 
would require similar coding which makes my eyes roll back in my 
head.

Is there an easier way to code my example?If not,whats the best way 
to get a grasp on AFL..Its brutal for a non programmer!!!

Thanks so much

Allan





Buy = 1; /* Go long all stocks*/
Sell = 0; 

// the system will exit 
// 50 of position if FIRST PROFIT TARGET stop is hit 
// 50% of position is SECOND PROFIT TARGET stop is hit 
// 100% of position if TRAILING STOP is hit 

FirstProfitTarget = 20; // profit 
SecondProfitTarget = 40; // in percent 
TrailingStop = 50; // also in percent 

priceatbuy=0; 
highsincebuy = 0; 

exit = 0; 

for( i = 0; i < BarCount; i++ ) 
{ 
   if( priceatbuy == 0 AND Buy[ i ] ) 
    { 
       priceatbuy = BuyPrice[ i ]; 
    } 

   if( priceatbuy > 0 ) 
    { 
       highsincebuy = Max( High[ i ], highsincebuy ); 

      if( exit == 0 AND 
          High[ i ] >= ( 1 + FirstProfitTarget * 0.01 ) * 
priceatbuy ) 
       { 
         // first profit target hit - scale-out 
         exit = 1; 
         Buy[ i ] = sigScaleOut; 
       } 

      if( exit == 1 AND 
          High[ i ] >= ( 1 + SecondProfitTarget * 0.01 ) * 
priceatbuy ) 
       { 
         // second profit target hit - exit 
         exit = 2; 
         SellPrice[ i ] = Max( Open[ i ], ( 1 + SecondProfitTarget * 
0.01 ) * priceatbuy ); 
       } 

      if( Low[ i ] <= ( 1 - TrailingStop * 0.01 ) * highsincebuy ) 
       { 
         // trailing stop hit - exit 
         exit = 3;    
         SellPrice[ i ] = Min( Open[ i ], ( 1 - TrailingStop * 
0.01 ) * highsincebuy ); 
       } 

      if( exit >= 2 ) 
       { 
         Buy[ i ] = 0; 
         Sell[ i ] = exit + 1; // mark appropriate exit code 
         exit = 0; 
         priceatbuy = 0; // reset price 
         highsincebuy = 0; 
       } 
    } 
} 

SetPositionSize( 50, spsPercentOfEquity ); 
SetPositionSize( 50, spsPercentOfPosition * ( Buy == 
sigScaleOut ) ); // scale out 50% of position