Re: [EquisMetaStock Group] Problem with if and isUndefined

["Roy Larsen" <rlarsen@xxxxxxxxxxxxxx>]

Stephane

Plot this exercise on any chart (unscaled) and take note of the interaction
of the four plots. Then try removing "Init OR" from both BarsSince() and see
what happens.

  {signal timing for a simple latch}

Set:=Cross(Mov(C,15,E),Mov(C,25,E)); Set+3.75;

Reset:=Cross(Mov(C,25,E),Mov(C,15,E)); Reset+2.5;

Init:=Cum(Set+Reset>-1)=1; Init+1.25;

Trade:=BarsSince(Init OR Set)<BarsSince(Init OR Reset);

Trade;



Roy





----- Original Message ----- 
From: "Roy Larsen" <rlarsen@xxxxxxxxxxxxxx>
To: <equismetastock@xxxxxxxxxxxxxxx>
Sent: Thursday, October 02, 2003 10:53 AM
Subject: Re: [EquisMetaStock Group] Problem with if and isUndefined


> Stephane
>
> Some suggestions.
>
> 1. Forget about using IsUndefined() - it's a waste of time and space
unless
> you use it to create the following "Initialised" (is valid) type of
formula.
>
> 2. Create an "Initialised" variable that gives a one bar spike when ALL
your
> other formulas are valid.
> I:=Cum("formula 1"+"formula 2"+"formula 3">some impossible negative #)=1;
> Note that for binary variables the formula can be as simple as this
> "I:=Cum((N+X)>-1)=1;"
>
> 3. Include "I OR " in all BarsSince(), HighestSince() or ValueWhen() etc.
> functions.
> BarsSince(I OR Fml("Wkly MACD Histogram")>0))
>
> The "I" variable is doing all that the IsUndefined() can do for you, it
will
> work with 6.52 as well as it works with 8.01, and most importantly it
gives
> a pseudo signal that is the best possible starting point for your useful
> plot. Well actually, as you know, the best starting point is bar one of
the
> chart, but IsDefined() and IsUndefined() are crippled functions and won't
> help you achieve anything in the normal N/A plot area anyway.
>
> The concept of the "I" variable creates a starting reference point where
all
> required variables are known to be valid. It is rarely of any consequence
as
> to what value a BarsSince() or ValueWhen() function returns at this point.
> What is important is that they return ANY value other than N/A.
>
> Roy
>
>
> ----- Original Message ----- 
> From: "stephanegranger_2000" <grangers@xxxxxxxxxxxx>
> To: <equismetastock@xxxxxxxxxxxxxxx>
> Sent: Thursday, October 02, 2003 10:09 AM
> Subject: [EquisMetaStock Group] Problem with if and isUndefined
>
>
> > Hi everybody,
> >
> > I'm currently trying to write a system tester for the Triple Screen
> > Trading system from Dr. Elder.
> >
> > I'm having a problem with assigning a value when IsUndefined is true.
> >
> > At some point, I need to compute how long the weekly MACD histogram
> > has been under 0.
> >
> > So this is what I wrote,
> >
> > nbBarsSinceBelowZero :=
> > If( IsUndefined(BarsSince(Fml("Wkly MACD Histogram")>0)),
> >     10000,
> >     BarsSince(Fml("Wkly MACD-Histogram")>0));
> >
> > When I plot the variable nbBarsSinceBelowZero, there is a large gap
> > at the beginning of the graph i.e. nbBarsSinceBelowZero is also
> > undefined but I would expect it to have a value of 10000 instead.
> >
> > However if I write
> >
> > If( IsUndefined(BarsSince(Fml("Wkly MACD Histogram")>0)),
> >     10000,
> >     0);
> >
> > I get 10000 at the beginning where I was getting no value and then a
> > lot of 0. So this is clearly a bug in MetaStock.
> >
> > Does anybody have a work around for that problem?
> >
> > Thank you,
> > Stephane
> >
> >
> >
> >
> >
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> >
> >
> >
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> >
> >
> >
> >
>
>
>
>
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