comparable units should be reduced on division

[VladimirAlexiev]

(This poor issue is looking for a home, was posted as unitsofmeasurement/uom-systems#182 but evicted from that project)

I use UCUM on the semantic web through LINDT (https://github.com/OpenSensingCity/jena-ucum by @maximelefrancois86, @Antoine-Zimmermann).

I'm trying to find the conversion factor of LB-PER-H for qudt/qudt-public-repo#285 (@steveraysteveray).
I tried this query at https://ci.mines-stetienne.fr/lindt/playground.html:

PREFIX cdt: <http://w3id.org/lindt/custom_datatypes#> 
select ("1 [lb_av]/h"^^cdt:ucum / "1 kg/s"^^cdt:ucum as ?conv) {}

The result is "1.0 s.[lb_av]/h/kg"^^cdt:dimensionless.
This might be formally correct but is highly useless because s.[lb_av]/h/kg is a dimensionless unit (the factor I'm looking for), but is left unreduced. I expect to get:

• 0.00012599803
• or 0.00012599803^^xsd:double
• or as last resort "0.00012599803"^^cdt:dimensionless
• (or a number approximately equal to this).

I'm posting this here (@grahamegrieve) instead of jena-ucum because I guess it comes from the core java-ucum engine.

Why is this important: java-ucum includes a bunch of conversion factors and this is the most natural way to get them out.

We have a big discussion at w3c/sparql-dev#129 whether UoM factors should be used as encoded in Java (LINDT), or should be explicitly put into triples (QUDT), and being able to get them out of java-ucum will provide a bridge.

unitsofmeasurement/unit-api#225 is a bit related (exposing the multiplication factor of a UnitConverter)

[grahamegrieve]

What would this look like as a test case in UcumFunctionalTests.xml (\src\test\resources)?

[VladimirAlexiev]

@grahamegrieve #20

[VladimirAlexiev]

Hi @grahamegrieve , any ETA on implementing this feature? I've provided a unit test

[grahamegrieve]

my apologies for ignoring this. Embarrassing I did it for so long. But what's the issue. The test passes as is?