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[amibroker] Re: Re: Negative volume on downloaded data from Yahoo



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Ahh, this would be a nice change to the database format.  I can then use V and OI fields for storing floating point numbers in my custom generated symbols via ATC!
 
JD
----- Original Message -----
Newsgroups: gmane.comp.finance.amibroker.general
Sent: Wednesday, April 26, 2006 7:20 AM
Subject: Re: Re: Negative volume on downloaded data from Yahoo

Hello,
 
Yes it divides volume by user-defined factor, so if you use 0.001
it will give you volume in thousand of shares. You can use 0.01 and you
will get volume in hundreds of shares.
 
As for "better" solution - yes as I already wrote some time ago Volume and OI fields
will be converted to floating point (instead of integer). You will lose some resolution
but you will gain larger dynamic range (upto 10 ^ 37 ). Since this change means
changing the format in which database is stored - it may mean breaking backward binary compatiblity
in databases (so, once it arrives, AB will convert the databases to a new format on-the-fly
(automatically), but once converted these databases won't be readable by older versions).

Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: yokehg
Sent: Tuesday, April 25, 2006 6:50 AM
Subject: [amibroker] Re: Negative volume on downloaded data from Yahoo

No, it is not Steve. It is not arbitrary number which will derived
from overflow. Overflow number (like negative volume in this case)
can be examined and with a little tricky formula can be revert-back
to the correct number (as long as we know how many overflow bit).
I agree that ABS function is misleading. Just try my formula, I
repeat again: 2*2147483647+V. Or this is my code:

  FixedVolume = IIf(V<0,2*2147483647+V,V);
  Plot(FixedVolume,.....

You may compare the result with the correct volume by looking at the
historical data Yahoo website. It will be exactly the same!

Unfortunately, starting from version 4.76, Amibroker will
automatically limiting the volume so that any volume greater than
2147483647 will be interpreted as 2147483647, which also misleading.
(My tricky formula cannot retrieve the correct number anymore :-( )

For Tomasz, thanks for the reply you gave. But doesn't your solution
will automatically divide (by 1000) all volume from any downloaded
symbol? I still hope you will do better than this, which I believe
it's a piece a cake for great developer like you.

--- In amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx, "Steve Dugas" <sjdugas@xxx> wrote:
>
> I don't think this would work as I believe overflow would result
in arbitrary number, so just converting it to positive would not
give actual volume.
>
> Steve
>   ----- Original Message -----
>   From: Chris Graham
>   To: amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx
>   Sent: Monday, April 24, 2006 2:33 PM
>   Subject: RE: [amibroker] Negative volume on downloaded data from
Yahoo
>
>
>   I use ABS( ) to convert the negative number into a positive one:
>
>   
>
>   MyVol = ABS(V);
>
>   Plot(MyVol,"Volume"...
>
>   
>
>   
>
>   regards
>
>   Chris
>
>
> -------------------------------------------------------------------
-----------
>
>   From: amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx
[mailto:amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx] On Behalf Of Terry
>   Sent: Tuesday, 25 April 2006 2:08 AM
>   To: amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx
>   Subject: RE: [amibroker] Negative volume on downloaded data from
Yahoo
>
>   
>
>   This has been discussed several times before. Back adjusted data
changes
>   the volumes so the adjusted price * adjusted volume still gives
correct
>   answers. Volumes can get so large they exceed 32 bit resolution
and
>   "roll-over" to a negative value. You can change how volume is
handled to
>   get Volume/1000 or whatever to avoid this.
>
>   Unfortunately, I do not remember the variable to adjust.
>
>   --
>   Terry
>   -----Original Message-----
>   From: amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx
[mailto:amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx] On
>   Behalf Of yokehg
>   Sent: Sunday, April 23, 2006 07:16
>   To: amibroker-hHKSG33TihhbjbujkaE4pw@xxxxxxxxxxxxxxxx
>   Subject: [amibroker] Negative volume on downloaded data from
Yahoo
>
>   I just notice that the negative volume on downloaded historical
data
>   from Yahoo! is due to overflow data in Amibroker. (It's not
Yahoo!
>   mistake which I've been thought so far. I'm sorry Yahoo! :-) )
>
>   So I convert the negative volume data, simply by using this
formula to
>   my favourit volume indicator:
>         2*2147483647+V
>   and it works as I expect.
>
>   However, lately on new version of Amibroker (or Amiquote?), it
looks
>   like that it has been 'fixed' (I'm not sure which version it has
been
>   started), so that the volume that is greater than 2147483647 is
>   interpreted as 2147483647, which I don't think it is not a good
idea.
>
>   Hope Amibroker will rectify this on next version.
>
>
>
>
>
>
>
>   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 other support material please check also:
>   http://www.amibroker.com/support.html
>
>
>   Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
>   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 other support material please check also:
>   http://www.amibroker.com/support.html
>
>
>
>
>
>
>
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