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Re: Are your Composites accurate???



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Richard,
Note please that in AFL the following results are true:
10-3^2=1
10+-3^2=19
!!!
Dimitris Tsokakis
--- In amibroker@xxxx, "Richard Alford" <richard.alford@xxxx> wrote:
> not in this universe :) It may not, in fact, matter since the 
exponentiation operator always (by some other convention?) follows 
the operand. Actually the "unitary" is a relatively new term (in the 
past 20 years) jumping out after I was well out of grad school (in 
mathematical physics) and before the programmers began to worry about 
the difference between subtraction and what I always interpreted as a 
simple negative number - the computer worries about such things, 
people don't. (I do realize the mathematical distinction has been 
around for centuries - just ignored like most math in the real world 
until it found a use.)
> 
> BTW - Multiplication and division are not generally on the same 
level ( My Dear Aunt Sally) for the antiques in the group; although, 
when in doubt most simply just hammer in parens by reflex - similar 
to the way a horse runs first and asks questions latter....
> 
> 
> I still think that this is a simple documentation error on TJ's 
part , and,personally, I find that comforting :)
> 
> Cheers,
> 
> Richard
> ----- Original Message ----- 
> From: Steve Dugas 
> To: amibroker@xxxx 
> Sent: Monday, April 29, 2002 8:34 PM
> Subject: Re: [amibroker] Re: Are your Composites accurate???
> 
> 
> It just occurred to me - maybe they are on the same level (like 
multiplication and division), so it does the negation first because 
it comes to it first?
> 
> Steve
> ----- Original Message ----- 
> From: Steve Dugas 
> To: amibroker@xxxx 
> Sent: Monday, April 29, 2002 9:08 PM
> Subject: Re: [amibroker] Re: Are your Composites accurate???
> 
> 
> Hi DT,
> 
> I must be missing something. I tried your plot, and -1^10 did 
evaluate to 1, like you say. But, if exponentiation takes precedence 
over negation (as shown in your table), how come it doesnt evaluate 
to -1, like this? :
> 
> -1^10 = -(1^10) = -(1) = -1
> 
> Steve
> ----- Original Message ----- 
> From: dtsokakis 
> To: amibroker@xxxx 
> Sent: Monday, April 29, 2002 12:16 PM
> Subject: [amibroker] Re: Are your Composites accurate???
> 
> 
> Herman,
> I really donīt know how do you realise things.
> Well, -1^10 is equal to 1.
> [It acts like (-1)^10 because of priorities in operators**
> [try Plot(-1^10,"",1,1);]
> -1*10^10 is a huge negative number
> Another Amibroker expression is -1e10, also negative enough.
> Your formula was not correct, because it was excuding stocks 
with 
> open==1 from counting.[see previous mails to you]
> DT
> **Operator precedence and the parentheses
> AFL supports parentheses in formulas. 
> 
> Parentheses can be used to control the operation precedence 
(the 
> order in which the operators are calculated). AmiBroker 
always does 
> operations within the innermost parentheses first. When 
parentheses 
> are not used, the precedence is as follows (higher precedence 
listed 
> first): 
> 
> No Symbol Meaning 
> 1 ^ Exponentiation 
> 2 - Negation - Unary minus 
> 3 * Multiplication  
> 4 / Division  
> 5 + Addition  
> 6 - Subtraction 
> 7 < Less than  
> 8 > Greater than 
> 9 <= Less than or equal to 
> 10 >= Greater than or equal to 
> 11 == Equal to 
> 12 != Not equal to 
> 13 NOT Logical "Not"  
> 14 AND Logical "And"  
> 15 OR Logical "Or" 
> 16 = Variable assignment operator 
> 
> The expression 
> 
> H + L / 2; 
> (without parenthesis) would be calculated by AmiBroker 
as "L / 2" 
> plus "H", since division has a higher precedence. This would 
result 
> in a much different value than 
> 
> (H + L)/2; 
> 
> --- In amibroker@xxxx, "Herman van den Bergen" <psytek@xxxx> 
wrote:
> > > -----Original Message-----
> > > From: dtsokakis [mailto:TSOKAKIS@x...]
> > > Sent: Sunday, April 28, 2002 11:13 AM
> > > To: amibroker@xxxx
> > > Subject: [amibroker] Re: Are your Composites accurate???
> > >
> > >
> > > Herman,
> > > I just noticed that your EMPTY is -1^10, ie equal to 1.
> > > So, your equivalent formula is
> > > EMPTY = 1;
> > 
> > Just realized that -1^10 is not equal to 1 but is -1 * 10^10
> > 
> > perhaps my code was OK anyway?
> > 
> > Take care,
> > Herman.
> > 
> > 
> > 
> > 
> > > AddToComposite(IIf(Open == 1,0,1),"~DataPresent","v",3);
> > > Do you have in the group of your gif some stocks with 
open==1 ?
> > > This would give some explanation.
> > > DT
> > > PS The huge negative symbol in AFL is -1e10
> > > --- In amibroker@xxxx, "dtsokakis" <TSOKAKIS@xxxx> wrote:
> > > > Of course I receive an identical result list with your
> > > > EMPTY = -1^10;
> > > > AddToComposite(IIf(Open == 
EMPTY,0,1),"~DataPresent","v",3);
> > > > Buy= 0;
> > > > f=Foreign("~datapresent","v");
> > > > Filter=f!=101;
> > > > AddColumn(f,"");
> > > > EXACTLY the same results.
> > > > To avoid any misuderstanding :your formula works, I 
just think
> > > > Amibroker does not use the open==EMPTY hypothesis, 
because if 
> the
> > > > ADLAC is not present on 16/4/2002, there is no 
reference for 
> ADLAC
> > > > this date.
> > > > My opinion is from experience, Tomasz knows how 
AddToComposite()
> > > > works.
> > > > DT
> > > > --- In amibroker@xxxx, "Dimitris Tsokakis" 
<TSOKAKIS@xxxx> 
> wrote:
> > > > > I respectfully disagree. If you are not concerned 
about bar-
> by-
> > > bar
> > > > accuracy
> > > > > than you are correct. In that case the "1" method 
works fine. 
> As
> > > > long as you
> > > > > know that this method will pick up holes of several 
days but 
> that
> > > > it will
> > > > > not pick up single bar holes.
> > > > >
> > > > >
> > > > > Herman,
> > > > > Of course we speak for daily search, bar-by-bar.
> > > > > I have in my ^NDX 4 experimental holes on
> > > > > 6/1/2000 [1], 15/2/2000 [1] and 1/3/2000[2]
> > > > > plus the missing ADLAC after 15/4/2002.
> > > > > As you see from the exploration, the population
> > > > > is different from 101 exactly these dates.
> > > > > I do not understand the conditions of your graph.
> > > > > The
> > > > > AddToComposite(1,"~count","v");
> > > > > Buy=0;
> > > > > scans bar-by-bar every stock for each date.
> > > > > If the stock is present, it adds an 1 and moves to 
the next 
> stock.
> > > > > If ADLAC is not present on 16/4/2002, then the sum 
will be 100
> > > > > for the certain date.
> > > > > It is impossible to have a 20% error, there should be 
another
> > > > > reason for your results.
> > > > > Dimitris Tsokakis
> > >
> > >
> > >
> > >
> > >
> > > Your use of Yahoo! Groups is subject to 
> http://docs.yahoo.com/info/terms/
> > >
> > >
> 
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