After a bit of experimentation, I can answer most of my own queries 1. SetBarsRequired - the backref parameter doesnt change the no of past bars that AB says it needs, but it changes the initial buffer (30 bars). So setbarsrequired(30, -1) has the same effect as setbarsrequired(-1, -1). In other words, we cant manually overrides the no of bars that AB internally decides it needs 2. if you enter setbarsrequired(0, 0); and A = MA(c, 50); the check and Profile tells you that you'll need 50 past bars. Fair enough. However, if you also put in B = MA(c, 50), it now says you'll need 100 bars. I can only say that AB always assumes the most pessimistic scenario in calcuating the past bars required. Thats probably explains why I end up with such a large no. for my AFL. while in reality it only uses a fraction of that past data.
And finally a question to Tomasz if I may, would you consider a means for the more adventurous users to overrides the defaults, In other words, means for me to tell AB I only want a certain number of past bars, sometime in the future. Paul. --- In [email protected], "Paul Ho" <[EMAIL PROTECTED]> wrote: > > Hi > I have just done some checking on my afls. I have been custom cuting > databases for a few years now to speed up run time. So I know > from experience how much data these afls need before the start date. > In looking at Code Check & profile, One of the AFLs state I need 4342 > past bars before the start date, which is approx 20 years of daily > data. I only have approx 18 years. So using QuickAFL wouldnt make any > difference to the execution time. But from experimenting with various > starting date in my custom database, I know that this afl only needs > 400 bars (1 & 1/2 years) of data before the start date. Obviously, > 400 bars back would make a marked difference in speed (thats why I > started this years ago). > I do not know why there is a difference between what AB calculates > and what it actually uses. > I also notice that setting the bars required manually to something > less than what Code and Profile says makes no difference to either > the results (which I would expect to ) or runtime. Is that correct > that setbarsrequired cannot be set to less than What AB calculates? >
