[Gmsh] Fourth Parameter in "Point" geometry..?

[Geordie McBain]

2011/7/6 rakesh patil <prakeshofficial at gmail.com>:
> Hello,
>
> I am new to GMSH and was just going through the tutorial. In the Geometry
> module, I just happen to come across this point:
>
> Point ( expression ) = { expression, expression, expression <, expression >
> };
>
> It says that first three expressions on the RHS is x, y, and z values of a
> particular point. What is <. expression> used for? It is mentioned in the
> documentation that
>
> the optional last expression sets the prescribed mesh element size at that
> point
>
> Any examples over this issue, so that the element size can be controlled by
> this optional parameter.?

This option is used in Tutorial 1

  http://geuz.org/gmsh/doc/texinfo/gmsh.html#t1_002egeo

though all points are given the same value so a uniform mesh is
produced, but you can edit one of them to get an idea.  See also
Tutorial 5, which does prescribe different values.