[amibroker] Trendline problem

["lamplowman" <lamplowman@xxxxxxxxxxxx>]

Hi Guys,

I've been able to get AB to plot On a Chart a line indicating my Buy
Price, Highest Price since bought, AND a percentage of Max profit
price that I'm willing to give back. Using a trendline (BP) I start at
the Buy price AND Date AND adjust it up as the price increases.  

This works great, as long as I have a trendline with ID Of "BP", if
NOT, AB goes beserk trying to rescale the Chart to make it all fit
from a price Of zero.

Now my problem is, is there any way to Check for the existence of
trendline "BP" AND How would I disable this part Of the formula for
stocks without a trendline.

Any ideas please,

Peter


_SECTION_BEGIN("Test");

/*  Display Percentage of highest profit  */
profit = Param("Profits",0.5,0.05,1,0.01);
Y=Study("BP", GetChartID()); // set the name of trendline here
P=BarIndex();
STARTX=ValueWhen(IsTrue(Y) AND IsEmpty(Ref(Y,-1)),P); // barnumber at
begin of trendline
STARTY=ValueWhen(IsTrue(Y) AND IsEmpty(Ref(Y,-1)),Y); // price at
begin of trendline
ENDX=LastValue(ValueWhen(IsTrue(Y),P)); // barnumber at end of trendline
ENDY=LastValue(ValueWhen(IsTrue(Y),Y)); // price at end of trendline
take =(endy - starty) * profit + starty;
gain = Prec((C - STARTY )/STARTY * 100,2);

Plot(HHV(starty,200), "Buy Price" , colorBlack ,styleDots + styleNoLine) ;
Plot(HHV(endy,200), "Highest", colorPaleGreen  ,styleDots + styleNoLine);
Plot(take,"Myprofit",ParamColor("Profit" , colorRed  ,styleDots +
styleNoLine);
Plot(C,"",1,64);

_SECTION_END();





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