At the risk of throwing more gasoline on this fire, I thought I would expand on my post #148811, which outlined a method for plotting a line segment on an existing price plot.
I compute 2 different regression fits to a QUADRATIC equation by method of Gaussian Elimination. I plot a 2 segments of the resulting parabolas (shorter and longer) on the price bar chart using the method in post #148811. I can slide the 2 segments back and forth along the time axis using a LookBack variable in the Parameters window. I can expand or contract the time axis (+ / - Zoom) and the display stays correct. I have been using this method since late 2004 - 5-6 years. Many different versions of AmiBroker. Hasn't broken yet. I create a ranking indicator from the QuadFits for about 800 ETF's that I track. Will probably add to the confusion: ReefBreak --- In [email protected], Tomasz Janeczko <gro...@...> wrote: > > Hello, > > It was explained many times on the list and it is documented in > http://www.amibroker.com/kb/2008/07/03/quickafl/ > (take a close look at the picture) > > that BarCount IS DYNAMIC, DEPENDENT on ZOOM. > > The code here: > > Plot( IIf( BarIndex()>= BarCount - EMABarsVisible21, EMA( C,21), Null ), "", > colorViolet,styleNoLabel |5 ); > > is totally WRONG. > > because it assumes that BarCount has any relationship with BarIndex(). > IT DOES NOT! > > The code will work only if ALL bars existing are in fact used by the > formula. > It is NOT the case in majority of cases. > > Only when you request all bars, or if you zoom out completely or if you > press "refresh all" for the very first > time it will use all bars. > Otherwise the formula use LESS BARS than all and quoted formula is > INCORRECT for all those cases. > > Again, reading it: > http://www.amibroker.com/kb/2008/07/03/quickafl/ > is necessary. > > Short advice: > DO NOT use BarCount for ANYTHING else than building a for loop that > iterates through array elements like > this: > for( i = 0 ; i < BarCount; i++ ) > { > array[ i ] = H[ i ] + L[ i ]; > } > > This is one and the only one use of BarCount (at least for people > without proper understanding of what was described in the > article pointed out above). > > > Best regards, > Tomasz Janeczko > amibroker.com > > On 2010-04-24 10:25, progster01 wrote: > > The working two-liner is great, and very clear to understand as given: > > > > bi = BarIndex(); > > Plot( IIf( bi< LastValue( bi ) - 21, Null, EMA( C, 21 ) ), "EMA", colorRed > > ); > > > > But why doesn't this other code that was discussed: > > > > Plot( IIf( BarIndex()>= BarCount - EMABarsVisible21, EMA( C,21), Null ), > > "", colorViolet,styleNoLabel |5 ); > > > > successfully accomplish the same thing? > > > > Understanding the difference, exactly, is much to be desired, IMO. Knowing > > the platform deeply enough to understand and avoid such pitfalls is the > > goal of many of us. > > > > I ask here on the list so that all may benefit from any answer that might > > be provided. > > > > > > --- In [email protected], Tomasz Janeczko<groups@> wrote: > > > > > >> Original question was: > >> > How to plot 21 days EMA only for the last 21 bars. > >> > >> And the answer is TWO liner: > >> > >> |bi = BarIndex(); > >> Plot( IIf( bi< LastValue( bi ) - 21, *Null*, EMA( *C*, 21 ) ), "EMA", > >> *colorRed* );| > >> > >> And it works in ALL AmiBroker versions. > >> > > > > > > > > ------------------------------------ > > > > **** IMPORTANT PLEASE READ **** > > This group is for the discussion between users only. > > This is *NOT* technical support channel. > > > > TO GET TECHNICAL SUPPORT send an e-mail directly to > > SUPPORT {at} amibroker.com > > > > TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at > > http://www.amibroker.com/feedback/ > > (submissions sent via other channels won't be considered) > > > > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG: > > http://www.amibroker.com/devlog/ > > > > Yahoo! Groups Links > > > > > > > > > > >
