|
PureBytes Links
Trading Reference Links
|
Hello,
For what is worth, exact description of the format is inside ADK.
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: Andy Davidson
To: amibroker@xxxxxxxxxxxxxxx
Sent: Wednesday, January 24, 2007 3:32 PM
Subject: Re: [amibroker] DateTime..what is the AB numerical format?
Tomasz,
I don't think you've designed *anything* plain stupid...!! Quite the opposite. However, you're right, I should have phrased myself better by saying that "this route would be cumbersome and unnecessary **compared to** manipulating the DateTime number value ** if ** that is possible?"...
Obviously it is NOT possible and, as I suspected, it was me that was missing something, not your good self. Hence the (dumb?) question. I'm sure though that you're aware of the phrase "the only dumb question is the one left unasked"?
So apologies for anything implied that was unintended and thanks for taking the time to explain the logic behind the design.
Regards,
Andy
Tomasz Janeczko wrote:
Hello,
>route seems cumbersome and unnecessary...
It amuses me to no end when such posts appear from time to time.
Every now and then someone starts thinking that I designed something
plain stupid.
And the answer always is: there is NOTHING in AmiBroker coming without
VERY GOOD REASON.
Microsoft DATE format needs 8 BYTES.
AmiBroker DateTime needs **half** of that (i.e. 4 BYTES).
It was designed to conserve space. While it is not a problem for one date/time,
once you want to store half million bars with timestamps such small difference
yields 2MB of RAM of savings PER SYMBOL.
Subtraction / addition by "number" does not work - it was never supposed to work that way.
The format was designed to be very fast at sec/min/hour/day/month/year <-> datetime conversion,
which is needed millions of times and not for numerical "subtraction" of dates which is never needed in AmiBroker
itself.
(If you now start to wonder why not use C time_t (4 bytes too) - then the answer
is - this format is also not good because it is valid ONLY for years 1970-2023,
while AmiBrokers' date time covers 1900-2155)
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "Andy Davidson" <AndyDavidson@xxxxxxxxxxxxx>
To: "Amibroker Yahoo Group" <amibroker@xxxxxxxxxxxxxxx>
Sent: Wednesday, January 24, 2007 1:54 PM
Subject: [amibroker] DateTime..what is the AB numerical format?
> I'm confused regarding the *numerical* format of DateTime.
>
> From my research there seems to be a factor of 10^9 difference between
> what AB reports as the DateTime number, using Now(Format=5), and what
> Microsoft say the value should be according to their standard for
> today's date.
>
> Can anyone explain why? My attempts to add/subtract numbers to the
> DateTime figure and then convert back to a string have failed
> miserably...I've guesstimated that 1-second is 6*10^16 in AB (as opposed
> to 1*10^7 on the MS help pages), but this does not seem to be the case.
>
> So it seems that I will have to go the long-winded way of breaking the
> date and time into components and playing with the arithmetic. Although
> within my understanding, this route seems cumbersome and
> unnecessary...is the conclusion correct that simple numerical
> manipluation of the DateTime number in AB is not possible?
>
> Grateful for any enlightenment.
>
> Andy
>
>
>
> Please note that this group is for discussion between users only.
>
> To get support from AmiBroker please send an e-mail directly to
> SUPPORT {at} amibroker.com
>
> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> For other support material please check also:
> http://www.amibroker.com/support.html
>
> Yahoo! Groups Links
>
>
>
>
>
Content-Description: "AVG certification"
No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.432 / Virus Database: 268.17.9/650 - Release Date: 1/24/2007 4:06 PM
|