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From Luc Maisonobe <>
Subject Re: proposal: numerical models [physics?]
Date Sun, 19 Apr 2009 14:45:57 GMT
Bear Giles a écrit :
> Hi, I was wondering if there would be interest in numerical models of
> physical constants.  For instance, saturation pressure of water vapor in
> air at a particular temperature.  It would also be appropriate to
> provide a method to get relative humidity from wet and dry bulb
> temperatures since it directly relates to this saturation pressure.  All
> of the models should be time-invariant, e.g., no historical weather
> observations.

I'm puzzled about this proposal. The scope seems completely unbounded
and will get out of hand quickly.
I would better see such a project under the wing of wikipedia or some
foundation like that.

> A simple unexplained model isn't very useful so there would be multiple
> elements:
> 1) a significant and attributed dataset.  You don't want three numbers
> somebody found in the back of some book, you want something like 1% of
> the values in the 74th edition of the CRC handbook of bobcats and
> weasels.  This would be provided as a XML document, and there would be a
> mechanism to support both multivariant data and sets of related values.
> I don't know how copyright plays into this since it's redistributing
> data.  I know that, in the past, it would have been okay in the US at
> least.  There are famous cases involving phone books,
> compilers/assemblers, etc., that established that you can copyright the
> presentation but not facts.  But I know publishers were trying to change
> that, and I'm not familiar with copyright law in other countries.

At least in France there is a real problem with data collections like
that. The law that governs intellectual property (the « code de la
propriété intellectuelle ») does have specific requirements about
database. Roughly, if someone has already established a database
containing anything, you cannot build a similar database containing only
the same data without infringing its rights.

> (It would also be nice to have tools to help people see if they screwed
> up the data when entering it.)
> 2) one or more numeric models, plus methods to calculate the appropriate
> coefficients from the data. You could have multiple models because of
> different needs.  E.g., one person requires a highly accurate model, but
> for somebody else the best fit could be something 'quick and dirty'
> since they're computing millions of values but don't need high accuracy.
> 3) analysis tools, to determine how accurate the model is.

I'm not sure the tools and the data should be wrapped together. They
simply don't have the same life cycle and are often not done by the same

> 4) (maybe) tools to create standard charts and graphs.  E.g., in
> meteorology there is a standard chart used with weather balloons because
> it makes it easy to determine if the atmosphere is unstable.  Having the
> ability to produce this chart + overlaid data would be very useful, but
> what format?  With what tools?  E.g., do you produce embedded postscript
> (for print media)?  An image?  A SVG?

This may be a project on its own.

> The second and third items could probably pull a lot from [math], or
> even reside in that project, with just the actual models and the
> underlying data in this project.  Obviously people should be able to
> download just the model.  On the other hand some people might want to
> write their own models and having the tools and data in place would be a
> godsend.

[math] should remain as independent to application as possible. Its goal
is to be a low level very reusable component. More specific applications
or other libraries are built on top of it in layered architectures.

> About myself: I have undergraduate degrees in both math and physics,
> most of an advanced degree in computer science, and have been working as
> a professional software developer for 25 years.  The motivation for this
> proposal is working at NOAA a decade ago - I worked with scientists who
> knew the science but didn't know they didn't know enough to write
> well-engineered numerical models.  The 'three unattributed data points'
> isn't a joke.  I've been planning to make this proposal for years, I've
> just never gotten around to it.

This is a real big project.


> Bear
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