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Tomasz,
I don't see anything unusual or surprising in what you say. The only
issue/question I have, and it is purely academic, is whether your
documentation is, in fact, in minor error by showing exponentiation as
higher precedence than the unary minus. Just for curiosity, can you give an
example where exponentiation has higher precedence? I have yet to see
anything in this thread that gives a surprising result to me.
Cheers,
Richard
----- Original Message -----
From: "Tomasz Janeczko" <amibroker@xxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Tuesday, April 30, 2002 3:36 AM
Subject: Re: [amibroker] Re: Are your Composites accurate???
> Richard,
>
> The - (unary minus) operator negates the value of the operand.
>
> The result of applying the unary minus operator to a signed operand is
> equivalent to the negative promoted type of the operand.
>
> For example, if quality has the value 100, then -quality has the
value -100.
>
> The unary minus has right associativity and higher precedence than most
other
> operators (except exponentiation)
> In the first Dimitris example the minus sign is treated as
> binary minus (regular subtraction) there fore the result is 10 - (3^2) =
10 - 9 = 1
> In the second Dimitirs example the minus sign follows addition
> operator. Addition (binary plus operator) expects numbers from left and
right side.
> This time minus is treated as unary minus operator
> So this is evaluated as:
>
> 10 + ( (-3)^2 ) = 10 + 9 = 19
>
> (right associativity of unary minus and precedence over binary plus
operator).
>
> Best regards,
> Tomasz Janeczko
> amibroker.com
> ----- Original Message -----
> From: "dtsokakis" <TSOKAKIS@xxxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Tuesday, April 30, 2002 9:07 AM
> Subject: [amibroker] Re: Are your Composites accurate???
>
>
> 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
> > > >
> > > >
> > > >
> > > >
> > > >
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