[Gmsh] unit in gmsh

[Geordie McBain]

2014-04-01 1:58 GMT+11:00 王学敏 <campusxuemin at gmail.com>:
> Dear gmsh user,
> Do you know the unit in Gmsh and freefem? How can I define unit in both
> software. Thank you so much.

Both programs are dimensionless; i.e. the unit of length is arbitrary,
it's up to you to interpret it however you like.
  It's good numerical practice in general to choose a system of units
(or, better yet, nondimensionalization) that yields numbers on the
order of unity.  This shows up in Gmsh when it has to use its
Geometry.Tolerance to decide if, e.g., two points are coincident; that
parameter can be modified but it defaults to 1e-6, so problems will be
encountered, for example, if a microscopic geometry is defined in SI
metres.