dolfin team mailing list archive

[Marie Rognes <meg@xxxxxxxxx>]

Anders Logg wrote:
> On Wed, Mar 31, 2010 at 09:21:50AM -0000, Chris Richardson wrote:
>   
> > Question #105900 on DOLFIN changed:
> > https://answers.launchpad.net/dolfin/+question/105900
> >
> >     Status: Answered => Open
> >
> > Chris Richardson is still having a problem:
> >
> > I still don't really understand why you need the extra qualification in these statements. Surely, the boundary
> > would be equally well defined without the x[1] clauses. Why do I need to put in the x[1] range so exactly?
> >
> >
> >    left = x[0] < DOLFIN_EPS and (x[1] > DOLFIN_EPS
> >                                       and x[1] < 1.0 - DOLFIN_EPS)
> >     
>
> If you don't include x[1] here, you will include the points (0, 0) and
> (0, 1). That means those point will be in "left" and thus
>
>   return on_boundary and not (left or right)
>
> will return false for those points. I assume you want to include those
> points in a no-slip boundary condition or similar.
>
>   
> >         right = abs(x[0] - 1.0) < DOLFIN_EPS and (abs(x[1] - .5) > DOLFIN_EPS
> >                                                   and x[1] < 2.0 - DOLFIN_EPS)
> >     
>
> This looks strange. What does x[1] range mean here?
>
>   


I don't know -- I suggested

	right = abs(x[0] - 1.0) < DOLFIN_EPS and (abs(x[1] - .5) > DOLFIN_EPS
                                                 and x[1] < 1.5 - DOLFIN_EPS)


--
Marie

> --
> Anders
>
>
>   
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