[Nexus] proposed additions to NXdata for non-linear scaling - to aid cbf interoperability

[Wintersberger, Eugen]

Hi folks

On Wed, 2014-02-19 at 10:11 +0100, Benjamin Watts wrote:
> Hi Jonathan,
>     This kind of thing has been discussed at previous NIAC meetings. 
> Your proposal makes for a simple change, but does more to push the 
> problem further away from yourself than to actually solve it. 

If I understand Ben correctly what he means is that the code working
with the stored data needs to do a lot of work to interpret it
correctly. 

> What we 
> really need is some "standard" way to present mathematical formulae in 
> general that is accessible across different programming languages. 

That's the right way to go.

> I 
> think maybe Eugen Wintersberger had a good suggestion, but I don't 
> recall any follow-up on it.

Hm - I cannot recall that I made a good suggestion on this. However,
what I would mot probably do is to use Python syntax to represent math.
This has two advantages: 

1.) an actual language can immediately execute the code
2.) it might be easy to write a parser for Python code in any other
language. 

In my opinion 2. is the the critical point. Once you start with this you
are basically inventing a new scripting language. Consequently, a
program which wants to use the data needs to parse this code and takes
the appropriate action which is not a trivial task. 

In addition one should be very careful with such things to not open
Pandoras box. I would restrict this to plain math (no loops, no
branching, etc.). Otherwise you really invent a new language. 

What is still open is how to fill the namespace for the code to execute.
Where should all the data mentioned in 

offset  + data**c

come from? 

At the end of the day there is one question we should seriously discuss:
how far do we want to go with math in Nexus?

regards
  Eugen

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