[Gmsh] PostView format and background mesh

[J S]

On 07/29/2013 10:57 PM, Geordie McBain wrote:
> 2013/7/30 j s <j.s4403 at gmail.com>:
>> Thanks for your response. What is the format for characteristic? The example
>> online, bgmesh.pos,  has 3 values. What do they mean?
> I don't know. I didn't really look into it at all; there's no need to.
>   The previously outlined procedure accomplishes the stated goal and I
> left it at that, regarding the .pos format as an intermediate black
> box.
I need to know how to specify the characteristic length in the .pos 
format.  The original mesh was originally generated by gmsh.  My program:
1. reads in a .geo file to get the original coarse mesh
2. performs a simulation on the gmsh mesh
3. calculates a characteristic length based on the existing points in 
the gmsh mesh

The missing pieces are:
4. write out a characteristic length in a format understood by gmsh.
5. have gmsh create a mesh based on my .geo file and my .pos file 
containing the characteristic lengths.

I need to know how to do this on 1d, 2d (triangle only), and 3d 
(tetrahedron only) meshes.

Thank you