Actually, in a related situation, this formula:
pds = Param("Periods", 20, 6, 252, 1);
DonchianUpper =Ref(HHV(C,pds),-1);
DonchianLower = Ref(LLV(C,pds),-1);
does NOT start to plot 21 days after the first bar of the data, but
starts with the second bar. In fact, the upper and lower channels
BOTH start with the close of the second bar. In my MS program such a
channel wouldn't begin to plot until there was the necessary number
of periods to calculate the indicator.
I don't view this as a bug but I would like to know why and how it
happens, along with a method for compensating (when appropriate).
Luck to all,
Sebastian
--- In amibroker@xxxxxxxxxxxxxxx, Terry <MagicTH@xxxx> wrote:
I don't know the answer to your question, but remember that
indicators
require time to stablize and AB automatically gets as many previous
bars
as necessary to do so. For example, you will need 100 bars to get
MA(C,100). If you don't use pre-existing bars, the value of the
array
will be either null or incorrect until 100 bars of data exist.
I do know if you check the equity curve there is no data before the
start date of your test regardless of how much data you have in
your
database.
Terry
onlyobsession2k3 wrote:
How come when I choose to view a specific date range in the auto-
analyzer and then Ref() outside of that range I don't get null
values?
For example if I have:
Buy = 1;
Test = Ref(Buy,-1);
Then I would expect on the very first bar of my date range
that "Test"
would NOT be 1, but it is. It seems to grab the data from the
previous
bar. How can I get it to treat that first bar like there is no
previous
data whatsoever?
Thanks,
Joel
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