I am sorry to hear that. Would have liked to play with it.
From: [email protected] [mailto:[email protected]] On Behalf Of reefbreak_sd Sent: Monday, April 26, 2010 10:39 PM To: [email protected] Subject: [amibroker] Re: Restricted Plot; Final test procedure; mainly a response to Mike and Tomasz I'm sorry that I've wandered off the topic of plotting a line segment on a bar chart. QuadFit was written by me from scratch and is proprietary. Doing a fit to a quadratic is tricky because a straight forward solution using Gaussian Elimination randomly produces wildly wrong values (blows up) every 100 or so bars. This requires a bunch of AFL coding tricks to keep the calculation stable and correct. ReefBreak --- In [email protected] <mailto:amibroker%40yahoogroups.com> , "Joris Schuller" <jschul...@...> wrote: > > Is the afl you describe below somewhere available? If so I would appreciate > a copy. > > > > From: [email protected] <mailto:amibroker%40yahoogroups.com> [mailto:[email protected] <mailto:amibroker%40yahoogroups.com> ] On Behalf > Of reefbreak_sd > Sent: Saturday, April 24, 2010 10:05 PM > To: [email protected] <mailto:amibroker%40yahoogroups.com> > Subject: [amibroker] Re: Restricted Plot; Final test procedure; mainly a > response to Mike and Tomasz > > > > > > 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] <mailto:amibroker%40yahoogroups.com> <mailto:amibroker%40yahoogroups.com> , > Tomasz Janeczko <groups@> 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] <mailto:amibroker%40yahoogroups.com> <mailto:amibroker%40yahoogroups.com> , > 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 > > > > > > > > > > > > > > > > > >
