# Surface Evolver Newsletter no. 1

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    		      Surface Evolver Newsletter Number 1
    			      January 25, 1993

                 Editor: Ken Brakke, brakke@geom.umn.edu

    Contents:
      Introduction
      Announcement
      Bibliography
      Latest features

    Introduction:

      The purpose of this Newsletter is to keep Surface Evolver users
      (and other interested parties) up to date and to promote interaction
      between those with like interests.  Contents will include:
         Latest features added to Evolver.
         Future plans for new features.
         Suggestions for new features, with the likelihood of their being
            added proportional to demand.
         Bibliography of papers using Evolver, hopefully with brief abstracts.
         Workshops, talks, etc. to be given.
         Descriptions of projects underway using Evolver.
         List of systems users have ported Evolver to.
         Anything else anybody would wish to contribute.

      Send contributions to brakke@geom.umn.edu.
      If you are not on the Newsletter mailing list and would like to be,
      send email to brakke@geom.umn.edu.

    Announcement:

      The possibility has arisen of porting Evolver to a CM5, which
      is a massively parallel machine.  The main benefit would be in
      speeding up iteration with many thousands of facets.  If anyone
      has a project which might benefit, please let me know.  Even if
      you never plan to run on a CM5 yourself, we would like to be able
      to cite types of applications that could benefit when requesting
      CM5 time to do the port.   -- Ken Brakke

    Bibliography:

    K. A. Brakke, The Surface Evolver Manual, version 1.87.  Research
       Report GCG45, The Geometry Center, 1300 South Second Street,
       Minneapolis, MN 55454. October, 1992.

         Every so often, The Geometry Center prints and binds a bunch
         of copies of the manual.  This is the latest.  Of course, it
         is not as up to date as the version in the ftp package.

    K. A. Brakke, "The Surface Evolver," Experimental Mathematics, vol. 1 (1992),
         no. 2, pp 141-165.

         A journal article giving a general description of the Evolver
         and some examples.  Good article to cite in your papers.

    K. A. Brakke, "The Opaque Cube Problem," Am. Math. Monthly, vol. 99,
        no. 9 (November, 1992), pp 866-871.

         Uses the Evolver to compute the area of a proposed solution to
         the Opaque Cube Problem, which is to find the least area surface
         that intersects all lines through a cube.

    K. A. Brakke, "Grain growth with the Surface Evolver,"
          Video Proceedings of the Workshop on Computational Crystal Growing,
          J. E. Taylor, ed., American Mathematical Society, Providence RI, 1992.

          Evolver starts with 100 cells in a square and evolves by mean
          curvature until equilibrium.

    M. Callahan, P. Concus and R. Finn, "Energy minimizing capillary surfaces
          for exotic containers,"  Computing Optimal Geometries,
          American Mathematical Society, Providence RI, 1991.

          Simulation of a Space Shuttle experiment done last year.
          See Science News for Aug. 22 1992 (I think) for a report
          on the Shuttle experiment.

    H. Mittelmann, "Symmetric capillary surfaces in a cube" and
         "Symmetric capillary surfaces in a cube Part 2: Near the
          limit angle," preprints.

          Evolver does families of fixed-volume bodies inside a cube
          with various contact angles.

    L. M. Racz, J. Szekely, and K. A. Brakke, "On some meniscus
          problems in materials processing," to appear in  Trans. Iron and
    	    Steel Inst. vol. 33(1993) no. 2.

          General description of Evolver and some applications to
          materials processing, such as liquid solder.

    J. Tegart, "Three-dimensional fluid interfaces in cylindrical
          containers," AIAA paper AIAA-91-2174, 27th Joint Propulsion Conference,
          Sacramento, CA, June 1991.

          Engineer at Martin-Marietta uses Evolver to simulate liquid fuel
          shape in weightlessness for Shuttle small fuel tank.

    Latest features:

    Latest ftp version is 1.88a, Jan. 6, 1993.  For those of you who
    haven't downloaded in a while, here's the history list from the manual
    for the past year:

    Version 1.76  March 20, 1992

         Autopopping and autochopping in string model for automatic
         evolution.

         Phase-dependent grain boundary energies.

         Approximate polyhedral curvature.

         Stability test for approximate curvature.

         Squared Gaussian curvature as part of energy only, not force.

         ``system'' command to execute shell commands.

         ``check_increase'' to guard against blowup during interation.

         ``effective_area'' to count only resistance to motion normal to surface.

          Runge-Kutta iteration.

    Version 1.80 July 25, 1992

          Command and query language much extended.

          geomview interface added. (A MUST HAVE for SGI machines. geomview
    	 available by ftp from geom.umn.edu.  Obsoletes MinneView.)

          Fixed area added as a constraint.

          Multiple viewing transforms can be specified in the datafile
          so one fundamental region of a symmetric surface can be
          displayed as the whole surface.

          Commands can be included at the end of the datafile, introduced
          by the keyword READ.

     Version 1.83 September 9, 1992

          Some alternate definitions of squared curvature added.
          Invoked by ``effective_area ON | OFF'' or
          ``normal_curvature ON  | OFF''.

    Version 1.84 September 10, 1992

          Shaded colors added to xgraph and cheygraph.

    Version 1.85 September 29, 1992

          Restriction of motion to surface normal added. Toggle
          ``normal_motion''.

          Squared mean curvature, gaussian curvature, and squared gaussian
    	curvature extended to surfaces with boundary.

          Datafile element attribute ``bare'' added for vertices and edges
          in soapfilm model so they won't generate erroneous warnings.

          Force calculation added for squared gaussian curvature, so it
          can be used in the energy.

          All prompts that require real value responses now accept
          arbitrary expressions.

     Version 1.86 October 19, 1992

          User-defined mobility added, both scalar and tensor forms.

          Default squared curvature works for 2-surfaces in $R^n$.

     Version 1.87 October 27, 1992

          ``close_show'' command added to close show window (the native
    	graphics window, not geomview).

          Graphics command checks string for illegal characters
    	before doing any transformations.

          Dihedral angles now work for 2-surfaces in any dimension.

          Permanent variable assignments may be made with ``\tt ::=''
          instead of ``:=''.  Such assignments will not be forgotten
          when  a new surface is begun.

          Conditional expressions of C form added: expr ? expr : expr.
          Useful for patching constraints  together.

    Version 1.88    December 16, 1992

          ``SET BACKGROUND color'' command added for native graphics.

          View transformation generators and expressions added.

          Exact bounding box calculated for PostScript files.

    Version 1.88a   January 6, 1993

          Default constraint_tolerance lowered from 1e-5 to 1e-12.

          Fixed bug in volume constraint calculation introduced in 1.88.

    Version 1.88b   (not in ftp yet)

          Postscript draws fixed and boundary edges in interior of surface.
          All internal graphics should be consistent in the special edges they
          draw (bare edges, triple edges, etc.).

          Viewing matrix can be read from datafile and will be dumped.
          Keyword VIEW_MATRIX

          Mod operator `%' added, and functions floor(), ceil().

          `rebody' command added to recalculate connected bodies
          after neck pinching and any other body disruption.

    End of newsletter.

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