
/*@ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 **
 **   This file is part of pTatin3d.
 **
 **   pTatin3d is a C library designed to solve variable viscosity Stokes
 **   flow problems in three dimensions. The flow problem is discretised
 **   using a mixed finite element (FE) formulation (Q2-P1) whilst Lagrangian
 **   state and history variables are discretised with the material-point
 **   method (MPM). Unique to this FE-MPM package is that we provide fast,
 **   parallel scalable matrix-free defintions for the Stokes operators which
 **   are utilized by a hybrid geometric-algebraic multi-grid preconditioner.
 **
 **
 **    Copyright (c) 2012
 **        Dave A. May [dave.may@erdw.ethz.ch]
 **        Institute of Geophysics
 **        ETH Zürich
 **        Sonneggstrasse 5
 **        CH-8092 Zürich
 **        Switzerland
 **
 **    pTatin3d is free software: you can redistribute it and/or modify
 **    it under the terms of the GNU General Public License as published
 **    by the Free Software Foundation, either version 3 of the License,
 **    or (at your option) any later version.
 **
 **    pTatin3d is distributed in the hope that it will be useful,
 **    but WITHOUT ANY WARRANTY; without even the implied warranty of
 **    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 **    See the GNU General Public License for more details.
 **
 **    You should have received a copy of the GNU General Public License
 **    along with pTatin3d. If not, see <http://www.gnu.org/licenses/>.
 **
 **
 **    Contributors:
 **    Jed Brown            [jed.brown@colorado.edu]
 **    Laetitia Le Pourhiet [laetitia.le@pourhiet@upmc.fr]
 **    Dave A. May          [david.may@earth.ox.ac.uk]
 **    Patrick Sanan        [patrick.sanan@erdw.ethz.ch]
 **
 **
 **    Contact:
 **    Dave A. May [dave.may@erdw.ethz.ch]
 **
 **    Institute of Geophysics
 **    ETH Zürich
 **    Sonneggstrasse 5
 **    CH-8092 Zürich
 **    Switzerland
 **
 ** ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @*/
