| Re: Physical constants in IDL with !CONST [message #82584 is a reply to message #82525] |
Thu, 20 December 2012 09:36   |
Heinz Stege
Messages: 189
Registered: January 2003
|
Senior Member |
|
|
On Thu, 20 Dec 2012 06:24:31 -0800 (PST), wlandsman wrote:
> I wonder if the constants should be !DtoR and !RtoD (or RADEG and DEGRA) to correct the earlier inconsistency in the ancient history of IDL. I'm not sure about this, though. --Wayne
>
A lot of discussions for a little thing, that everyone can do her or
himself within a startup file.
However, I think Wayne is absolutly right.
A similar point is, that I wouldn't name the elementary charge "eV". I
know, there is a name conflict with the Euler's number. However the
Euler's number can simply be calculated by number=exp(1d). Therfore I
suggest to simply remove it from the table.
Please realize, that most of the "constants" are from physics and
chemistry and the Euler's number is a mathematical number which never
will change. (You may argue, that pi also is a mathematical constant,
however it is needed [even though by definition] for the calculation
of the magnetic constant mu0=4d*!dpi*1d-7)
The name "ev" for the elementary charge is confusing, because the
definition of the elementary charge constant has nothing to do with
the energy unit "electron volt". The reason for 1 eV being 1.602...
10^-19 J only reflects, that changing the potential of a charge e
about 1 V means an energy change of 1.602... 10^-19 J.
Thats what I wanted to say.
Cheers, Heinz
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
