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Hi,
Can you not solve the problem by (effectively) re-defining varx
within the expression i.e.
varx = C<Ref(L,-6) AND vary <6 AND NOT(C<Ref(L,-12) AND vary <6);
Haven't tried this and the presentation could possibly be tidied a
bit. (Depending on what, exactly, you are trying to achieve, the very
last term might need to be "Ref(vary,-6)<6" or some such.
Brian
--- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@xxx>
wrote:
>
> It depends. The loop is general-purpose solution and works always.
>
> In some cases loops can be eliminated using Cum(), ValueWhen(),
> AMA, AMA2.
>
> Best regards,
> Tomasz Janeczko
> amibroker.com
> ----- Original Message -----
> From: "sidhartha70" <sidhartha70@xxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Thursday, September 18, 2008 9:56 AM
> Subject: [amibroker] Re: Recursive Boolean Expressions... Possible?
>
>
> > Can I ask the master...?? TJ... Does this kind of expression
> > absolutely require a loop structure?
> >
> > TIA
> >
> > --- In amibroker@xxxxxxxxxxxxxxx, "gp_sydney" <gp.investment@>
wrote:
> >>
> >> Graham,
> >>
> >> That doesn't work either, in the general case, as varx is still
not
> >> dependent on previous values of varx, only on previous values of
your
> >> first "temp" statement.
> >>
> >> Consider the simpler case:
> >>
> >> temp = BarIndex() < 10;
> >> varx = temp AND NOT Ref(temp,-1);
> >>
> >> temp now has the first 10 bars set to one and all other bars set
to
> >> zero. varx will have the first 11 bars set to zero, since Ref
(temp,-1)
> >> is one (actually the first bar will probably be null) and then
all
> >> subsequent bars will also be zero since temp is then zero.
> >> Consequently, varx would be completely zero, except perhaps for
the
> >> first null.
> >>
> >> Assuming this did work as suggested, compare to:
> >>
> >> varx = BarIndex() < 10 AND NOT Ref(varx,-1);
> >>
> >> Actually if the first bar was null due to Ref(varx,-1) being
null,
> >> then varx would end up completely full of nulls (a problem to be
wary
> >> of with nulls in loops). But say the first bar ended up being
zero
> >> (perhaps the nz function was used), then the second bar would be
one,
> >> since BarIndex is less than 10 and Ref(varx,-1) refers to the
first
> >> bar which we just said was zero. The third bar would be zero,
since
> >> Ref(varx,-1) now refers to the second bar which we just set to
one,
> >> and the fourth bar would be one again. This would continue up to
the
> >> 10th bar, after which all bars would be zero due to the BarIndex
term.
> >> The first 10 bars of varx alternating between one and zero make
the
> >> result different to the first version.
> >>
> >> Regards,
> >> GP
> >>
> >>
> >> --- In amibroker@xxxxxxxxxxxxxxx, Graham <kavemanperth@> wrote:
> >> >
> >> > try this
> >> > temp = C<Ref(L,-6) AND vary<6;
> >> > varx = temp AND NOT Ref(temp ,-6);
> >> >
> >> > --
> >> > Cheers
> >> > Graham Kav
> >> > AFL Writing Service
> >> > http://www.aflwriting.com
> >> >
> >> >
> >> >
> >> >
> >> > 2008/9/18 gp_sydney <gp.investment@>:
> >> > > No, you can't do that as the right-hand expression is
evaluated
> > on the
> >> > > whole array before anything is assigned to the left-hand
variable.
> >> > > That means that "varx" is effectively constant during the
expression
> >> > > evaluation for the whole array. It's essentially the same as:
> >> > >
> >> > > temp = IIf(C<Ref(L,-6) AND vary<6 AND NOT Ref(varx,-
6),True,False);
> >> > > varx = temp;
> >> > >
> >> > > To do what you are suggesting would require a loop.
> >> > >
> >> > > Regards,
> >> > > GP
> >> > >
> >> > >
> >> > > --- In amibroker@xxxxxxxxxxxxxxx, "sidhartha70"
<sidhartha70@>
> > wrote:
> >> > >>
> >> > >> Hi All,
> >> > >>
> >> > >> Is it possible to have recursive boolean expressions...?
i.e. the
> >> true
> >> > >> or false of the current value of the array depends on
whether a
> >> > >> previous value of the array is true or false.
> >> > >>
> >> > >> So for example,
> >> > >>
> >> > >> varx = IIf(C<Ref(L,-6) AND vary<6 AND NOT Ref(varx,-
6),True,False);
> >> > >>
> >> > >> Would that work... or are recursive booleans like this not
> > allowed??
> >> > >>
> >> > >> TIA
> >> > >>
> >> >
> >>
> >
> >
> >
> > ------------------------------------
> >
> > Please note that this group is for discussion between users only.
> >
> > To get support from AmiBroker please send an e-mail directly to
> > SUPPORT {at} amibroker.com
> >
> > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> > http://www.amibroker.com/devlog/
> >
> > For other support material please check also:
> > http://www.amibroker.com/support.html
> > Yahoo! Groups Links
> >
> >
> >
>
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