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Latches and MS function language really don't have anything to do with
intelligence per se. It's a matter of practice and understanding of
what each of the MS functions do and the values they return.
First from Roy, "A `latch' is a device that stores and holds, or
remembers, a particular event or condition. A `binary latch' can be
set to one of two values (normally zero and one but not necessarily
so), while a `price latch' can be set to virtually any value one could
think of. Each type has both advantages and disadvantages that will be
mentioned as appropriate."
This is key. Right now on your chart you see multiple buy signals.
Your expert is recognizing every buy event that is true, not just the
first one. So it is not storing the condition when it first occurs.
So you need to look at example 2. First you want to set the memory of
the first buy signal. That's the set signal part of the code. The set
signal is the buy formula. The reset is when the buy condition no
longer exists. In other words you have a sell condition. There can be
many buy signals that occur between the first one and when a sell
signal is encountered. Once a sell signal shows up. It's game over.
The next buy signal after a sell signal is the first one in a new
sequence of buy signals.
Once the first buy signal is hit, then you want the buy condition to
stay true until a sell signal resets it. So each bar that the buy
signal is still true on prevents MS from treating it as a "new" buy
signal.
set:=buysignal;
reset:=sellsignal;
Init:= Cum(set+ Reset>-1)=1;
Trade:= BarsSince(Init OR Set)<BarsSince(Init OR Reset);
Trade AND Alert(Trade=0,2);
Init means the set and reset signals are valid. It solves a problem
with the BarsSince function returning an invalid response. Essentially
the cum value is going to be =1 if a legitimate buy signal and sell
signal has occurred in the past.
How would you know that BarsSince can return a not valid signal?
Intelligence! No, only experience with MS coding will tell you that.
You get a few N/A screwing up your code, then you'll look for a
solution and eventually you'll either quit out of frustration or
you'll come up with some logic to get around the problem. Every coding
language has problems.
Next Trade says that if the bars since the first buy signal is less
than the bars since a sell signal, then the sell condition remains
true and is set to 1. The last line Trade and Alert means a buy signal
must exist and it didn't exist on previous bars. In other words both
conditions must be true to hold the expert in a buy state.
Write your expert with this last bit of code in it. Code the buy
conditions, usually buy:= whatever and sell:= whatever .
Then set:=buy;
reset:=sell;
etc.
That will be your entry expert. Your exit expert is set up the same
way except the exit or sell condition goes in the set and the buy
condition goes in the reset for the exit expert.
This one one kind of latch, or condition state code. Some types of buy
signals require a different kind of condition state code. In addition
there are other types of code which can hold a state condition as
positive.
In addition on the MS forum there is a latch code dll that you can
download.
Here's the syntax for the latch in the Forum dll. The four parameters
are Long Entry, Long Exit, Short Entry and Short Exit. I suggest you
only use the first two and leave the "short" parameters at zero. The
Forum.dll file is around 188-189KB. Pay attention to the size of the
file to make sure you have the current version.
ExtFml( "Forum.Latch", , , , )
I think the forum latch code should be built into the formula language
and put in the manual. But so far it isn't. Unfortunately BP, if you
want to use custom code in your experts, then you have no choice but
to learn the basics.
I have learned to write code that is sloppy and less than elegant, but
it works. I don't worry too much about the MS function language
because as I've said many times, making money trading never depends on
programming complex formulas, etc.
You'll get a little help for awhile on some of the forums. But once a
newbie has had time to learn things for themselves, the help will dry up.
Only a dozen or so people supply coding help on all of the forums so
they remember who they've helped and how often. Unfortunately some of
the newbie's think the people on the forums are saps and will code
everything they want for them for free and forever. They don't want to
do the homework and take the tests. They want someone else to do it
for them, but they want the grade and the degree.
So you and I have little choice but to struggle through this
ourselves, and I can tell you I hate spending time coding MS. I have a
large code library that I have collected over the years and basically
I can piece most things together by looking at other formulas and
doing some trial and error.
I use very little code in my buy and sell formulas. They're pretty
simple. Most of the code gets used in my analysis screens, but in the
long run I think I would do just as well if I didn't use them. They
give me some comfort emotionally and intellectually.
They are a lot of newbies who make breathless posts wanting code for
some magic formula they got from a guru of sorts. They often think
that if they just had that code they would make money. Here's the
bottom line. Equis can code anything. If there were formula's that
they could put into MS that would help traders, especially new
traders, make money, they would bust their butts to get those formulas
into MS because sales would take off like a rocket. Instead they
supply vague notions of systems that often can't be tested and that
work well only when the market is in a strong trend. Why might that be?
I hope this bit of latch code gets you where you want to be with your
experts. All those signals are frustrating. I remember that time well.
If you don't get it to work out, you can put your buy and sell code
into the highlight tab in the expert. Color code the buy and sell
conditions with a different color and as long as you have a buy
condition your bars (or whatever) will remain that color. It's the
same as getting one buy and one sell signal.
Super
--- In equismetastock@xxxxxxxxxxxxxxx, "Big Papa" <denver69692002@xxx>
wrote:
>
> Well, I thought I was a bit intelligent until I tried to read, re-
> read and decipher the Latch article.
>
> My hats off to Mr. Larsen for his intelligence. I've also looked on
> Equis under latches and Googled Metastock Latches which gives me
> several more various articles from Larsen.
>
> Still struggling. I'd appreciate a guiding hand to push me a bit.
>
> First, are the latches their own seperate indicator or are they
> built into the buy and sell alerts on the expert advisor?
>
>
> Thanks.
>
>
>
> --- In equismetastock@xxxxxxxxxxxxxxx, superfragalist <no_reply@>
> wrote:
> >
> > Look in the files section and download the Using Latches article.
> That
> > will explain how to stomp out those unwanted buy signals all over
> your
> > chart.
> >
> > Super
> >
> >
> > --- In equismetastock@xxxxxxxxxxxxxxx, "Big Papa" <denver69692002@>
> > wrote:
> > >
> > >
> > > I am having issues with my expert advisor.
> > >
> > > I have taken an indicator and dumped it into the expert advisor.
> > > Such as sell when C>HHV(C,7).
> > > It shows a sell sign at the right time, but then shows another
> sell
> > > sign each time that condition is true, regardless if a buy sign
> has
> > > generated or not.
> > > So now, my charts look like 20 sell signs right in a row. My
> charts
> > > look like a neighborhood in foreclosure!! I could probably deal
> with
> > > it, but looks terrible.
> > >
> > > Do I have to use the Write If function in the expert advisor to
> only
> > > have it show up once? It seems like I would need some logic to
> say If
> > > condition X, then sell, but then only show again if condition W
> (buy)
> > > is generated.
> > >
> > > Thanks.
> > >
> >
>
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