|
PureBytes Links
Trading Reference Links
|
Hi William,
A couple of quick comments in line below . . .
Monday, September 15, 2003, 5:53:50 AM, you wrote:
WP> This is a perfect opportunity for AFL beginners to learn by
WP> DOING, as Ron said just having to get it all down in a readable
WP> fashion is an effort that will pay dividends.
WP> Below, I have written a non-techie answer to a post by Glen which
WP> asked about the setting n=1 in AA.
WP> Also, please suggest changes if you have idea's of how to make
WP>this description clearer.
WP> =======================================================================
WP> When you set n=1, AA will check only the latest dated bar in your
WP> database in order to see if your AFL conditions has been met on
WP> only the latest dated bar. However, while Amibroker is executing
WP> your particular AFL instructions, it still needs to
WP> retrieve data from earlier dated bars in order to produce
WP> things such as moving average calculations, and other
WP> calculations that will be required by your AFL coding.
I would change "latest dated bar" (above) to "most recent bar". I am
also not sure that the additional information about what AB is doing
while it is executing the instruction is relevant. It is nice to
have, perhaps, but it also could be confusing, because I think some
people might take the following logic after reading it: "Oh, it needs
to retrieve data from earlier bars, so how the heck do I make sure
that it can do that?"
WP> When you set n=10, Amibroker will follow exactly the
WP> same procedure that it did when you set n=1. The only difference
WP> is , Amibroker will first check the bar that is positioned 10
WP> periods back from the present bar. A period will be in seconds,
WP> minutes, hours, days, months, or whatever you happen to
WP> have available in your database for Amibroker to check. Once
WP> Amibroker is through checking the 10'th bar back, it
WP> moves forward to check the 9'th bar, then on to the 8'th
WP> bar, and so on, till it finally checks the n=1 bar last.
WP> ====================================================================
I will give my shot here:
In the AA window, what does 'n' equal?
'N' equals the number of most recent bars that you want to analyze in
an AA analysis.
When you set n=1 in the AA window, the analysis will apply only to
the most recent bar in your database. If your database is daily, it
will apply only to the most recent day. If your database uses
another time period (5-minute bars, for example), the analysis will
apply only to the most recent 5-minute bar. Whatever the period of
time for the bars in your database, the number you specify as 'n'
will tell AA to analyze that number of most recent bars in your
analysis.
If you set n=10 in the AA window, the analysis will first be done on
the 10th most recent bar, then the 9th most recent, etc., until the
most recent bar (n=1) is done. So in this case, the analysis would
be done 10 times . . . for each issue that you are analyzing. If you
analyze 1000 issues, the analysis would be done 10,000 times.
Tip:
If the condition you are filtering for (the output you want to see)
is likely to be frequently true, setting 'n' to a large number and
including a large number of issues to be tested will likely produce a
very large output. Realize that every bar for every issue where the
condition was true during the period of 'n' will be output. If you
test 1000 issues setting n=25, and the condition is likely to be true
for approximately every 5th bar (20 percent true), you can expect an
output of approximately 5,000 lines (1000 x 25 x 20%).
Practical application:
You have an EOD buy or sell signal that you want to test for each
night: You create an exploration and run it each night, including all
the issues you want to test for, and setting n=1 to see if that
condition was true for any of those issues on the most recent bar.
You want to generate a list of daily prices for the past week to send
to a friend: You create an exploration that will output the price
data, include all the issues you want the data for, and set n=5 (this
assumes a daily database). The output will be five lines for each
issue, the five most recent bars.
======
I'm sure somebody can improve upon this. But what I would key in on
is keeping the basic explanation as clutter free as possible, then
including some kind of tip (might be a warning, too) and a practical
application.
Yuki
------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for Your HP, Epson, Canon or Lexmark
Printer at Myinks.com. Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/l.m7sD/LIdGAA/qnsNAA/GHeqlB/TM
---------------------------------------------------------------------~->
Send BUG REPORTS to bugs@xxxxxxxxxxxxx
Send SUGGESTIONS to suggest@xxxxxxxxxxxxx
-----------------------------------------
Post AmiQuote-related messages ONLY to: amiquote@xxxxxxxxxxxxxxx
(Web page: http://groups.yahoo.com/group/amiquote/messages/)
--------------------------------------------
Check group FAQ at: http://groups.yahoo.com/group/amibroker/files/groupfaq.html
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|