# [e-gold-list] Re: UNITS, UNITS, UNITS, UNITS... please e-gold

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[EMAIL PROTECTED], you make a good point, and e-gold will
refine that conversion factor to make it more accurate. send
me your e-gold account number for a reward bounty.

from a scientific basis, i opine that the most precise
and accurate conversion factor between ounces and
grams to be exactly:
31.1034768
which is derived from the NIST data stating that:
1 grain = 64.79891 milligrams (*exactly* because bold font)
(see http://physics.nist.gov/Pubs/SP811/appenB9.html)
also a troy ounce is *exactly* 480 grains, so we arrive at
64.79891 mg / grain * 480 grain / troy ounce * 1/1000 g/mg =
31.1034768 grams per troy ounce

(for some independent form of verification, i find this number
in several web based troy ounce <-> gram conversion tables)

e-gold account balances are tracked by weight to 6 decimal
places - in troy ounces. lets see what a difference the conversion
factor might make. a spend can only occur to a precision of
6 decimal places in ounces. for a spend denominated in grams,
can a conversion factor of 31.103 vary the weight amount when
performed in ounces to 6 places...

in some cases, the conversion factor used for a spend denominated in
grams to 5 or more decimal places may effect the sixth decimal
place of the actual e-gold spend (in ounces). for example a spend of
0.99995 grams will convert to
.99995g = .032150 oz.
using the 31.103 factor and
.99995g = .032149 oz.
using the exact conversion factor above.

note that this variation in the 6th place is 1 millionth of an ounce.

but also note...it is not possible for e-gold to transfer **exactly**
.99995g between accounts regardless of the conversion factor - e-gold
is currently accounted in ounces to six places. i.e. convert either
ounce amount in the above example back to grams...you'll get:
0.99996145 for the first part
or
0.999945675643 something for the second.
*neither of which is .99995g.*

that is what happens when things are converted with a floating point
ratio. if you want exactness in your programmatic interfaces with the
current e-gold system you need to perform your accounting in ounces
to 6 places, and perform your sci and automated spends with e-gold
using
those ounce amounts.

if your external system uses grams and you wish to interface with
the current e-gold system, i can think of 2 options to choose
between...
1. if your system uses grams to 4 decimal places or less (i.e. no
fractional tenths of milligrams) the current conversion factor works
as good as any more precise conversion factor - *but you still need
to realize that e-gold spends are actually performed after converting
to ounces*.
2. convert your spends to ounces using whatever method you'd like
prior to presenting data to e-gold. use 6 decimal places.

jay w.
[EMAIL PROTECTED]

> A bold statement!
>
> What does e-gold say?
>
> >e-gold is using the wrong gram-ounce conversion.  The correct unit
> >is one troy ounce = 31.103477 grams, exactly, not 31.103, which is
> >what e-gold currently uses.  I can document the source of the
> >31.103477 if you care,
>
> Yes, document it thoroughly please.
>
> >but it is the correct value; any other value is wrong,
> >according to generally acknowledged standards bodies.  Please fix
> >this.  It makes a difference for those of us who are trying to
> >interface with e-gold and keep our accounts in grams, not ounces.
> >

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