Re: [Bug-gsl] Electron charge in CGS(E)

[Evgeny Kurbatov]

On Sun, 19 Jul 2009 12:16:43 +0100
Brian Gough <address@hidden> wrote:

> At Mon, 13 Jul 2009 13:34:05 +0400,
> Evgeny Kurbatov wrote:
> > I think I found a wrong value of electron charge in gsl_const_cgs.h
> > file.  Its value correspond to the MKS system of units, i.e.
> > 1.602176487e-19 while the true value in CGS(E) is 4,80320427e-10
> > (see http://en.wikipedia.org/wiki/Elementary_charge or slightly
> > different value on http://www.astro.wisc.edu/~dolan/constants.html).
> 
> Hi, 
> 
> Thanks for the bug report.  The situation with the file
> gsl_const_cgs.h is problematic -- it has been replaced with
> gsl_const_cgsm.h, which should have the correct CGSM values.  The old
> file had to be kept because some programs depended on the name.
> 
> I'm going to put a #warning macro into the gsl_const_cgs.h to make the
> situation clearer.

Hi, Brian

There are four different system of electromagnetic units standing on
CGS as the base system: ESU CGS (or CGSE), EMU CGS (or CGSM), Gaussian
(or symmetric, CGSS) and Heavyside-Lorentz (see
http://en.wikipedia.org/wiki/Cgs for all of them).  Those are different
in definition of dimension constants such as vacuum permittivity, vacuum
permeability etc.  In CGSE system the electron charge is 4.80320427e-10
but in CGSM it is 1.602176487e-20.  So gsl_const_cgsm.h has the right
value of electron charge but for CGSM system.  If the idea of
gsl_const_cgs.h was to contain the constants from base CGS system
only, we have to remove electron charge from it, then create
gsl_const_cgse.h for right CGSE values.  Actually we have to add
constants of vacuum permittivity and permeability for completeness.  If
nobody dealing with it, I can because I'm interested in it.

Best witches,
Evgeny