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## Re: [femlisp-user] femlisp examples

 From: Nicolas Neuss Subject: Re: [femlisp-user] femlisp examples Date: Wed, 26 Sep 2007 13:43:32 +0200 User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux)

```"Jason Sidabras" <address@hidden> writes:

> I am still learning what I have to solve but I believe that is close. The
> current plan is to formulate the equation based off of the electric
> vector potential (A) and scalar magnetic potential (phi).

Shouldn't this be the other way round?  Magnetic vector potential and
electric scalar potential?

> curl (sigma^-1 curl A) =  -i omega mu (A - div phi)

Divergence of a scalar potential does not make sense.

> I am waiting to get:
> BOSSAVIT, A,: 'On the numerical analysis of eddy current problems',
> Comput. Methods Appl. Mech. & Eng., 1981,27, pp. 303-318
>
> Which, according to the abstract, takes Maxwell's equations and forms the
> variational formula which I should be able to solve with FEM for eddy
> current problems.
>
> Do you have any good references on edge elements, their importance and
> how to create them? I have read a number of references in trying to
> understand this problem and they do mention the use of edge elements, but
> no real detail into what is different between the element methods. My
> current understand is the edge elements are mainly just the elements in
> creating the boundary.

Possible references: the book of Monk, two recent books of Demkowicz, and
maybe also an Acta Numerica article of Hiptmair.

>     This file should be loaded automatically.  What does the variable
>     FL.MESH::*TRIANGLE-PATHNAME* contain?  Does it work, if you set it to the
>     location of your triangle binary?  (However, this should be found
>     automatically, if it is in your path, see the lines at the beginning of
>     #p"femlisp:src;mesh;triangle.lisp".)
>
>  none of the objects exist that are part of the Shewchuk library in
> #p"femlisp:src;mesh;triangle.lisp"

The file triangle.lisp is not part of the Shewchuk library, but the Femlisp
interface to this library.  The function TRIANGULATE-2D writes out a
boundary polygon, then calls 'triangle', then reads in the generated mesh.

HTH, Nicolas

```