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Re: An approach to describing the relationships betweenunits-o

• To: "Roger L. Costello" <costello@m...>
• Subject: Re: An approach to describing the relationships betweenunits-of-measure
• From: "Emmanuil Batsis (Manos)" <mbatsis@n...>
• Date: Mon, 21 Jul 2003 15:13:51 +0300
• Cc: xml-dev@l...
• In-reply-to: <3F1BCFC6.D23FEA71@m...>
• Organization: Netsmart S.A., Greece
• References: <3F1BCFC6.D23FEA71@m...>
• Reply-to: mbatsis@n...
• User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4)Gecko/20030624

Hi Roger,

Roger L. Costello wrote:
> Recall that <kilometer> may be considered as a function:
> 
>     kilometer(length(Yangtze)) --> 6340
> 
> "kilometer maps the length of the Yangtze to 6340."


Does not feel right. For the above to be a meaningfull function, one 
should assume that Yangtze has a length property in some internal 
representation (attribute value) L so that length is

function length()
{
    return this.L;
}

and kilometer is

function kilometer(someNumber)
{
    return toKilometers(someNumber);
}

but parts of the equasion are missing:

1) What kind of unit is used to internally store L?
2) What formula should be used to convert L to kilometers in kilometer()?

Thus, the signature to kilometer indicates a function signature where 
two parameters are passed, one for the number to convert and one for the 
type to convert from:

function kilometer(someNumber, someType)
{
    if(someType.equals("meters"))
       return fromMetersToKilometers(someNumber);
    // rest of elseif statements mapped to expected
    // input types here
}

which is bad, as the kilometer function can only accept a finite number 
of input types at first glance.

IMHO the above practically becomes something like:

L = length(Yangtze)
T = L.type()

kilometer(L,T)

 > Issue #1: Above I said that:
<snip about="tolerance" eg="(6340 k, 3914 m) in {k, m | k = m * 1.62}"/>



Cause tolerance should be specified as above. If tolerance is just a 
third parameter, it's power grows weaker while numbers get higher.

Unless tolerance is a float used to construct

k >= m * 1.61 && k >= m * 1.63

from

k, m | k = m * 1.62

as in
tolerance = 0.01

Very interesting approach. Please do give this stuff an online home or 
something.

-- 
Manos Batsis

Netsmart S.A.

Snail mail:
Panepistimiou 58,
10678, Athens, Hellas

URL:    http://www.netsmart.gr
Email:  mbatsis at netsmart dot gr
Tel:    (+30) 210 33 02 608
Fax:    (+30) 210 33 02 658
FOAF:   http://forte.netsmart.gr/foaf/manos_foaf.rdf

• Follow-Ups:
  • Re: An approach to describing the relationships between units-of-measure
    • From: John Cowan <cowan@m...>

• References:
  • An approach to describing the relationships between units-of-measure
    • From: "Roger L. Costello" <costello@m...>

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