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GP,
Thank you for taking the time to help me with the auto trendline code I
greatly appreciate it.
When I first tried your original code for the start and end bars:
startbar = LastValue(ValueWhen(xx, x, 2)); // Yesterday's start bar
-original
endBar = LastValue(ValueWhen(xx, x, 1))-1; // Bar before today's start
bar -original
It gave me a trendline through the (o+c)/2 of yesterdays second bar and
todays first bar and it was consistent
with every stock I tried. I finally came up with a modified version that
produced a trendline through the (o+c)/2
of yesterdays first and last bar that works with every stock:
startbar = LastValue(ValueWhen(xx, x, 2)-1); // Yesterday's start bar
-modified
endBar = LastValue(ValueWhen(xx, x, 1))-2; // Bar before today's
start bar -modified
The modified code only works with the LineArray function as when I use
the slope formula it
gives me a small offset from the (o+c)/2.
I still need more work on this array stuff because the light has not
gone on quite yet.
Once again I am grateful for the help.
Thank you,
Kind regards
Geary
--- In amibroker@xxxxxxxxxxxxxxx, "gp_sydney" <gp.investment@xxx> wrote:
>
> One issue I can see is that you choose the start and end bars by
> comparing their 'y' values to startvalue and endvalue1. If there are
> multiple bars with the same (O+C)/2 value, then the startbar and
> endbar formula will find the most recent occurrences, not the ones
> used to obtain startvalue and endvalue1.
>
> It seems to me you're going about this backwards. I'd find the bar
> numbers first and then their values, not the other way around. You
> already have the start bars marked in the "xx" array, so to get the
> actual bar numbers (or array indices), just use something like:
>
> x = Cum(1)-1; // Can also use BarIndex();
> xx = DateNum() != Ref(DateNum(),-1);
> startbar = LastValue(ValueWhen(xx, x, 2)); // Yesterday's start bar
> endBar = LastValue(ValueWhen(xx, x, 1))-1; // Bar before today's start
bar
>
> The 'y' values are then just:
>
> ocAvg = (O+C)/2;
> startOc = ocAvg[startBar];
> endOc = ocAvg[endBar];
>
> although you should test both bar values for being in the valid range
> 0 to BarCount-1 first. You can plot the line the fundamental way using
> the formula:
>
> slope = (endOc-startOc)/(endBar-startBar);
> trendLine = slope*(x-startBar) + startOc;
>
> or just use the LineArray function:
>
> trendLine = LineArray(startBar, startOc, endBar, endOc);
>
> Note that these plots will only look correct with linear price scale,
> unless the price range is small. If you're using semilog, then the
> line formula is:
>
> slope = log10(endOc/startOc)/(endBar-startBar);
> trendLine = startOc*(10^(slope*(x-startBar)));
>
> Hope this helps, although note that I haven't actually tried any of
> this code.
>
> Regards,
> GP
>
>
>
> --- In amibroker@xxxxxxxxxxxxxxx, "convertah" convertah@ wrote:
> >
> > Hello and good day,
> > I have been trying to write a formula that will draw an automatic
> > trendline through the, (O+C)/2, of the first and last five minute
> > candles of yesterday. I'm new to AFL and had fun trying to get this
far,
> > which was only accomplished by searching mail archives,the users
guide,
> > knowledge bases and, even the "new" googlesearch.
> >
> > The trendline works perfectly on some stocks but other stocks will
have
> > the line through one but not both of the candles; while other stocks
> > show no connection with the trendline at all.
> >
> > Thoughts on how to make this really work would be greatly
appreciated.
> >
> > This is the code:
> >
> > x = Cum(1);
> >
> > xx = DateNum() !=Ref (DateNum(),-1);
> >
> > startvalue = LastValue(ValueWhen( Ref (xx,79), (O+C)/2,1 )); /*
> > (O+C)/2 of first bar of yesterday */
> > endvalue1 = LastValue(ValueWhen( Ref (xx,1), (O+C)/2,1 )); /*
> > (O+C)/2 of last bar of yesterday */
> >
> > startbar = LastValue( ValueWhen( (O+C)/2 == startvalue, x, 1 ) );
> > endbar = LastValue( ValueWhen( (O+C)/2 == endvalue1, x, 1 ) );
> >
> > Aa = (endvalue1-startvalue)/(endbar-startbar);
> > b = startvalue;
> >
> > trendline = Aa * ( x - startbar ) + b;
> >
> > Plot( Close, "Price", colorBlue, styleCandle );
> > Plot( trendline, "Trendline", colorRed );
> >
> > Thank you,
> > Kind regards
> >
> > Geary
> >
>
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