> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of
> David Nickerson
> Sent: 10 November 2006 03:18
> To: For those interested in contributing to the development of CellML.
> Subject: Re: [cellml-discussion] Quick questions about units...
>
> >> CellML processing software is not required to check for
> dimensional
> >> consistency at the equation level (but validating software would
> >> probably want to). Software is also not strictly required
> to convert
> >> at the connection level, although appendix C defines how
> to do this
> >> if software implements the functionality (CCGS and
> mozCellML do have
> >> this functionality). Derived units are converted into the
> set of base
> >> units, and base units are compared (and constant factors
> multiplied
> >> and raised to the appropriate powers, to get the
> conversion factor).
> >
> > Exactly and I guess this is the point I was trying to make: maybe
> > CellML processing softwares should be forced to do those checks?
>
> While I'm not sure we should be making it compulsory for
> CellML compliant applications to completely support units
> validation and conversion, I do think we need to think a bit
> about this issue to address the following example...
>
> Currently, when I read my model in to an application which
> has complete units support (such as JSim) it may generate and
> insert appropriate unit conversion factors within my
> equations (and variables) when compatible but different units
> have been used. Then I can perform simulations using the
> model and get a given set of results.
>
> However, when I read my model into an application with less
> than complete support for units those conversion factors may
> or may not be added to the equations and variables and when I
> run the same simulations I get a different set of results for
> essentially the same input model.
Yes and I have to admit that COR would be one of those programs that would
give you different results indeed. We are going to sort it out though...
> Both applications can be seen as behaving correctly....I guess.
>
> I'm really not sure how to address this other than suggesting
> that applications clearly state their units support status
> and provide some way to easily locate (and view?) instances
> where unit conversion factors have been added to the model
> (either at the connection level or within equations).
To make it simpler in terms of user interface, I think it should be done at
the connection level. At least, that's where we intend to do it in COR.
Alan.
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