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> -----Message d'origine-----
> De : Bob Fulks [mailto:bfulks@xxxxxxxxxxxx]
> Envoye : dimanche 29 juillet 2001 00:20
> A : omega-list@xxxxxxxxxx
> Objet : RE: TradeStation Precision - Summary
>
>
> At 11:32 PM +0200 7/28/01, pierre.orphelin wrote:
>
> >Maybe there is something else on this list who understand the precision
> >calculus allowed display concept.
> >
> >I cannot believe that it is only a french specificity...
>
> Please read "The Perils of Floating Point" at:
>
> <http://www.lahey.com/float.htm>
>
> Perhaps it explains it better than I have been able to.
I read it before and read it again today.
Nothing to say, the article is well writen but deals with math precisions,
limitations inherent to float in math calculus.
All of this is correct.
>
> This is simply the way the floating point representation works. That
> is a fact in any language.
Yes
>
> TradeStation uses single-precision floating point representation so
> it has these problems.
>
Yes, after 6th digit
> Excel uses double-precision floating point representation (probably)
> so it has these problem too, but they are 10 million times smaller
> than the problems in TradeStation because it uses more precision, so
> these errors are usually not noticeable in Excel.
Certainly, and is a dog too
But if we stay with the 5 -6 digit precision as used in technical analysis,
this is not an issue, and this is where we do not feel the same needs in TS.
The minimum requirement for price analysis is achieved with TS Floats, it
could be better for other purposes, but this is not the TS target.
TS is a compromise between simplicity , speed and acceptable technical
analysis precision based on price data.
You may ask these requirements for special uses, but TS is not guilty of not
respecting this minimum contract.It does not provides the extended contract
that you wish...
>
> Even with this extra 10 million X in precision, the people who wrote
> the Excel functions knew about these issues and made sure the
> algorithms they used were not compromised by the accuracy issues even
> as small as they were. The total Excel product (complete with it's
> function library) can be counted on to provide accurate answers.
Yes (but read more accurate answers if needed by the user)
>
> Other programming systems such as MatLab also go to great lengths to
> assure that the accuracy of their product with its function libraries
> give very accurate answers. That is what the world has come to expect
> in such products.
Obviously, this is not the TS niche. It has been the TradeLab niche, but you
know the story.
There is not a valid market for such product, and in the meantime, better to
compile DLLs using doubles for special apps in TS.
I do not think that you will require double precision for all of your
indicators, no ?
>
> The problems are VERY NOTICEABLE in TradeStation so people who write
> functions and programs for TradeStation have to be aware of the
> issues and "work-around" them. The people who wrote the TradeStation
> functions either were not aware of the problems or didn't care about
> the accuracy so the functions and indicators shipped with the product
> have noticeable errors. That is a fact - not my opinion.
This is an opinion, because you suspect people behind TS of not having done
their homework.
I only say that they have done what was necessary to respect the minimum
specification, and this is an opinion too that I can easily change into a
fact...
The fact is that TS precision has known limitations, and that these
limitation are diversely viewed according to different users that do not
have the same requirements for the same product, or not the same priority in
their analysis of the problem that they attempt to solve with the tool.
All of us agreeing that the minimum contract is respected ( price precision
for the final result), we could close this thread.
>
> My initial post in this thread tried to point out how to "work-around"
> the issues, because unfortunately, Omega doesn't seem to want to fix
> them.
Who knows...?
Sincerely,
Pierre Orphelin
www.sirtrade.com
TradeStation Technologies representative in France
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