Hello,
1. It is your call. 64-bit version is able to use more than 4GB of memory and
is slightly faster. But only supports IB and IQFeed real time plugins.
2. Yes, both versions (32-bit and 64-bit) use same data files and you can use
same database.
Best regards,
Tomasz Janeczko
amibroker.com
On 2010-07-20 13:33, sanjiv wrote:
> Hello Mr. Janeczko,
>
> Though now all my machines are Win7_64, I am continuing with Ami_Pro_32. Does
> the benefit you described below warrant that I should migrate toward
> Ami_Pro_64 ?
>
> Further, will the AmiBroker Native database being updated via ASCII import be
> compatible across Ami_32 and Ami_64 interchangably.
>
> With regards
>
> Sanjiv Bansal
>
>
>
> --- In amibroker@yahoogroups.com, Tomasz Janeczko wrote:
>>Hello,
>>
>> There is* no problem* with adding 1000 to positionscore.
>>
>> You are adding the same value to *all* positionscore numbers and by doing so
>> you will NOT change the ordering (ranking) even if 8th significant digit is
>> subject to standard IEEE 32-bit rounding,
>> because larger number will still be larger after adding constant, no matter
>> if result is rounded in 8th significant place or not.
>> So it is irrelevant.
>>
>> Also, it is important to understand that AmiBroker AFL arrays use standard
>> 32-bit floating point, recommended reading:
>> http://en.wikipedia.org/wiki/IEEE754
>>
>> The same is used by majority of T/A applications since there is really no
>> point in wasting memory on more.
>> Using 32-bit floating point has two main advantages:
>> a) consumes HALF of memory required for doubles (this *is* important, more
>> important that you think, because
>> if you have for example 50 bars, in floats it is 2MB and it fits into
>> CPU cache, while in doubles it would be 4MB and
>> may not fit into CPU cache).
>> b) 32-bit floating point numbers can be computed much faster. It simply
>> takes less processor cycles to compute 32-bit float than
>> 64-bit float. 64-bit version of AmiBroker is going even further and is using
>> SSE2 instructions. This means that vectors of 4 single-precision
>> numbers are processed in parallel using single SSE2 instruction on SINGLE
>> processor.
>> This gives more speed on single core than achievable using multiple cores.
>>
>> Note also AmiBroker *does use double precision (64bit)* where it is
>> necessary (for certain internal calculations)
>>
>>
>> Best regards,
>> Tomasz Janeczko
>> amibroker.com
>>
>> On 2010-07-20 01:37, Paul D wrote:
>>>
>>> Oh whoops. Sorry - apparently I didn't read your question carefully enough.
>>> Not sure how to solve the precision problem.
>>>
>>> Paul
>>>
>>>
>>> *From:* Herman
>>> *To:* bistrader
>>> *Sent:* Mon, July 19, 2010 3:19:01 PM
>>> *Subject:* Re: [amibroker] Why does adding 1 to PositionScore cause
>>> problems?
>>>
>>> You are exceeding the 7-digit precision (32 bits?) of AmiBroker.
>>>
>>> herman
>>>
>>> *> I have an afl with PositionScore at 77.904854 for one
ticker. PositionScore also has negative values for
certain tickers for certain dates. So, I add 1 to
PositionScore as I want all PositionScore values to be
positive. I do so as followings and notice that 77.904854
changes to 10077.90527. Happens to many tickers. Not
what I expected. I expected values to increase by exactly 1.
PositionScore = rank; // 77.904854 is one value observed
PositionScaore = PositionScore + 1; // expect to get
10077.904854 but get 10077.90527
I know I am missing something with precision. I looked
in help but could not find anything to help. Does anyone
know what is going on and where in documentation?
Thanks.
>>>
>>>
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>>>
>>>
>>> *
>>>
>>> * *
>>> * *
>>>
>>>
>>>
>>>
>
>
>
>
>
> IMPORTANT PLEASE READ
> This group is for the discussion between users only.
> This is *NOT* technical support channel.
>
> TO GET TECHNICAL SUPPORT send an e-mail directly to
> SUPPORT {at} amibroker.com
>
> TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
> http://www.amibroker.com/feedback/
> (submissions sent via other channels won't
