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 <gro...@...> 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 500000 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 <psy...@...> > > *To:* bistrader <amibroker@yahoogroups.com> > > *Sent:* Mon, July 19, 2010 3:19:01 PM > > *Subject:* Re: [amibroker] Why does adding 10000 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 10000 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 10000. > > > > > PositionScore = rank; // 77.904854 is one value observed > > > PositionScaore = PositionScore + 10000; // 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. > > > > > > > > > ------------ --------- --------- ------ > > > > > **** 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 <http://amibroker.com> > > > > > TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at > > > http://www.amibroke r.com/feedback/ <http://www.amibroker.com/feedback/> > > > (submissions sent via other channels won't be considered) > > > > > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG: > > > http://www.amibroke r.com/devlog/ <http://www.amibroker.com/devlog/> > > > > > Yahoo! Groups Links > > > > > > > > * > > > > * * > > * * > > > > > > > > >
