I am pleased to announce the availability of Version 1.1 of MGGHAT.

MGGHAT (MultiGrid Galerkin Hierarchical Adaptive Triangles) is a
FORTRAN program for the solution of second order linear elliptic
partial differential equations of the form

    d    du      d    du
 - -- (p --)  - -- (q --) + ru = f   in D
   dx    dx     dy    dy

with boundary conditions of the form

                             u = g   on d1

        du  dy      du dx
      p --  --  - q -- -- + cu = g   on d2
        dx  ds      dy ds

where p>0, q>0, r, f, c and g are functions of x and y, D
is a polygonal domain in R^2 (possibly with holes), d1 U d2 is
the boundary of D, and d/ds is differentiation with respect to a
counterclockwise parameterization of the boundary (x(s),y(s)).
The second form of the boundary condition, called the natural
boundary condition, reduces to the Neuman boundary condition
when p=q=1.

MGGHAT uses a finite element method with linear, quadratic or
cubic elements (user selectable) over triangles.  The adaptive
refinement via newest vertex bisection and the multigrid iteration
are both based on a hierarchical basis formulation.  Run time and
a posteriori graphical displays are made with gnuplot.

MGGHAT is available from netlib.  It can be obtained, for example,
by sending the message "send index from pdes/mgghat" (without the
quotes) to netlib@research.att.com.

MGGHAT can also be obtained from MGNET (multigrid network) by
annonymous ftp to casper.cs.yale.edu in directory mgnet/mgghat.

A hypertext version of the User's Guide can be accessed by your
favorite WWW brower at the URL
http://gams.nist.gov/reports/mgghat/userguide/userguide.html

The major changes from version 1.0 to version 1.1 are:

o Added the capability to save the program state and evaluate
  the solution from the saved state.  This is useful for systems
  of equations, time dependent problems, nonlinear equations, etc.

o Added example user files for a system of equations and for a
  time dependent problem.

o Custom run-time graphics replaced with gnuplot.

o Added an (optional) Tcl/Tk based menu for addition/deletion of
  graphical displays during run time, and rotation of 3D plots.

o Repackaged to be more user oriented.

o Now have makefiles for AIX, Convex (not vector), Cray (not vector),
  HPUX, IRIX, Linux, and SunOS.  Makefiles are more user oriented,
  and, when available, have an auto-double option.

o Default parameter values are set in block data rather than the
  user main program.

o New User's Guide written.

o Several minor bug fixes and robustness improvements.


William F. Mitchell                            | mitchell@cam.nist.gov
Applied and Computational Mathematics Division | na.wmitchell@na-net.ornl.gov
National Institute of Standards and Technology |
Gaithersburg, MD 20899                         |