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Hello,
1. Logarithm of ZERO is Undefined in math.
THerefore log scale must not be used for non-positive values
2. When using scripting you have to add
SetBarsRequired function at the top of your formula
to give hint how many bars you need in your
scripting part:
http://www.amibroker.com/guide/afl/afl_view.php?name=SETBARSREQUIRED
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "andy_kovacs" <andy_kovacs@xxxxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Wednesday, April 16, 2003 9:24 PM
Subject: [amibroker] Jscript functions
> Tomasz -
>
> Ive found the reason for the logarithmic graphs being plotted from
> zero: the j-script function is returniung zero values.
>
> So the problem isnt with the plotting, it seems that the new version
> doesnt like this j-script code and just returns zero for the whole
> array. I tested the same function on the previous version works fine.
>
> Any ideas?
>
> Andy
>
> --- In amibroker@xxxxxxxxxxxxxxx, "andy_kovacs" <andy_kovacs@xxxx>
> wrote:
> > Tomasz -
> >
> > Some time back someone posted an excelent piece of trailing stop
> > code "ATR BASED STOPS with JScript" which I have included in my
> > systems. In the tests I did, this code gave better results than
> the
> > in-built function, so I kept using it rather than re-coding using
> > the applystop function.
> >
> > My default for graph display in preferences is Logarithmic, but I
> > dont actually draw the "price" indicator on the chart; I use plot
> > (c,"Name of System: close=",colorblack,stylebar); This means I
> have
> > to tick the box "logarithmnic" in the gridlines part of the
> > indicator window to get a logarithmic display.
> >
> > When the longstop and shortstop (the results of the java
> functions)
> > are plotted either side of the price, the graph is crammed right
> at
> > the top of the page and the scale starts from zero instead of some
> > value near the minimum of the price range. As the graphs before
> were
> > normal, I hadnt noticed, but Ive just tested a few codes and each
> > time I use the java trailing stop code the graph re-sets itself to
> > start from zero in both normal and logarithmic mode (as set in
> > indicator window, NOT preferences).
> >
> > When I edit out the plot(longstop,"etc........) and change the
> > indicator window back to normal (untick box) the graph is still
> > plotted from zero, but it looks fine. Just in log mode it squashes
> > up at the top of the page and becomes unusable.
> >
> > Is this normal? Am I doing something wrong somewhere or is it a
> > quirk of the program?
> >
> > Heres the code for the stops, but I guess you already know it....
> >
> > //********** ATR BASED STOPS with JScript *********//
> >
> > EnableScript("jscript");
> >
> > //first the raw stop functions are defined based on ATR-depending
> > distance to the close price
> >
> > range = multiplier*ATR(Len);
> > rawlongstop=C-range; //raw long stop
> > rawshortstop=C+range; //raw short stop
> >
> > //two JScript functions for the stops are defined
> > <%
> > //function for the longstop
> > function f_longstop(rawstop,baseprice,Length){
> >
> > //"importing" the AFL functions into JScript
> > Len = AFL(Length);
> > Ls=VBArray(AFL(rawstop)).toArray();
> > bp = VBArray(AFL(baseprice)).toArray();
> >
> > //the stop is calculated in the loop
> > for(i=Len+1;i<Ls.length;i++){
> > if(bp[i]>=Ls[i-1]){Ls[i]=Math.max(Ls[i],Ls[i-1]);}
> > }
> >
> > return Ls;
> > }
> >
> > //function for the shortstop
> > function f_shortstop(rawstop,baseprice,Length){
> > //"importing" the AFL functions into JScript
> > Len = AFL(Length);
> > Ss=VBArray(AFL(rawstop)).toArray();
> > bp = VBArray(AFL(baseprice)).toArray();
> >
> > //the stop is calculated in the loop
> > for(i=Len+1;i<Ss.length;i++){
> > if(bp[i]<=Ss[i-1]){Ss[i]=Math.min(Ss[i],Ss[i-1]);}
> > }
> > return Ss;
> > }
> > %>
> > //*********** End of JScript *****************//
> >
> >
> > Andy
>
>
>
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