[CF-metadata] bounds

[Bryan Lawrence]

Hi Folks

Speaking as a person who has done budget studies in the past, I think exact 
comparisons are the way to go ... not only in the variables, but in their 
coordinates ...

> What would be a "contrived" example where 1E-5 would not work ?  We are
> not trying to preserve numerical results in the face of complex
> algorthims, just trying to answer the question if the bounds are
> continuous.

Ok, if my cells are in the mesosphere of an atmospheric model, particularly 
one that includes the troposphere, then the cells are going to be pretty 
deep, possibly a couple of orders of magnitude in difference in pressure 
coordinates .... if I then couple on a thermospheric model, and I'm stupid 
enough to carry on using  pressure as the vertical coordinate, then my cells 
will become many orders of magnitude apart ... I can imagine failing the 
above equality test in that situation ... even when the cells are contiguous 
... other coordinate systems at that altitude may have even more problems.

As a personal aside:

>Someone has tried to create a CF netcdf file and bungled it, by not 
>getting the coordinate bounds correct. So I am going to use NcML to fix 
>the problem, by adding some of the values in "by hand".

I know you are using ncml to generate catalogues, and so I can see the 
incentive for *fixing* the ncml associated with files , however, if folk are 
using the ncml to instantiate code for doing things with the data based on 
the ncml, I think it would be dangerous to rely on "by-hand-fixes" in
the markup that are not representative of the actual data files ...

.... having said that, I know about real users and what they do ...

Cheers,
Bryan

-- 
Bryan Lawrence, Head NCAS/British Atmospheric Data Centre
web: www.badc.nerc.ac.uk  phone: +44 1235 445012
CLRC: Rutherford Appleton Laboratory, Chilton, Didcot, OX110QX, UK