[CIG-ALL] PyLith v1.7.1 feature release

[Brad Aagaard]

Greetings,

I am pleased to announce the release of PyLith 1.7.1, a finite-element
code designed to solve dynamic elastic problems and quasi-static
viscoelastic problems in tectonic deformation.

This release fixes a couple of bugs in PyLith v1.7.0. The PyLith v1.7
release series adds several new features to PyLith, including (1)
user-friendly interface for computing Green's functions, (2) output of
solution field at user-specified locations, (3) plane strain version
of the Drucker-Prager elastoplastic rheology, (4) prescribed spatial
and temporal variation of fault tractions with spontaneous earthquake
ruptures, (5) ability to use PETSc GPU solvers, (6) user-specified
start time for simulations, and (7) elastic prestep in quasi-static
simulations is optional.

We strongly recommend all users of previous PyLith releases switch to
this latest release. In addition to adding features this release also
fixes a minor parallel processing bug related to fault friction in
quasi-static simulations.

See the README file for changes required to switch to the v1.7.x
release series from previous versions.

You can download the source code and binaries from

     http://geodynamics.org/cig/software/packages/short/pylith

Detailed installation instructions for the binary packages are in the
User Manual with detailed building instructions for a few platforms in
the INSTALL file bundled with the PyLith Installer utility.


RELEASE NOTES - PyLith v1.7.1

* Bug fixes

   - Fixed a couple of bugs in the spontaneous earthquake rupture for
     quasi-static problems when running in parallel. These prevented
     the nonlinear solve from converging and erroneously generated
     fault-opening in a some cases.

   - Minor updates to the documentation and manual. Added Green's
     function examples to the manual.

RELEASE NOTES - PyLith v1.7.0

* New features

   * User-friendly interface for Green's functions

     A new problem type provides a user-friendly interface for
     computing Green's functions associated with fault slip for complex
     spatial variation in elastic properties. See examples/2d/greensfns
     in the tutorials for examples.

   * Output of solution field at user-specified locations

     Added a new output manager for interpolation of the solution field
     to user-specified point locations. This feature is useful for
     comparison of the solution with observations and in computing
     Green's functions. See examples/3d/hex8/step19 and
     examples/2d/greensfns in the tutorials for examples.

   * Plane strain version of Drucker-Prager elastoplastic model

     Added a plane strain version of the Drucker-Prager elastoplastic
     model. Additionally, the user can now select whether to use an
     inscribed, intermediate, or circumscribed fit to the Mohr Coulomb
     criterion.

   * Spatial and temporal variation in tractions for spontaneous
     earthquake rupture

     Switched from a simple constant spatial variation in initial fault
     tractions to the more flexible spatial and temporal variation
     consistent with the Dirichlet, Neumann, and point force boundary
     conditions. Also added a switch to turn on/off applying prescribed
     fault tractions when the fault opens; the default behavior is to
     stop applying prescribed fault tractions when the fault opens, but
     turning this off allows simulation of dike intrusions via
     prescribed fault tractions. See examples/3d/hex8/step20 in the
     tutorials for an example of how to specify fault tractions with
     the new implementation.

   * Ability to use PETSc GPU solvers

     Added ability to build PyLith with either double (default) or
     single precision floating point values to facilitate use of
     GPUs. In order to use PETSc GPU solvers, CUDA and cusp must be
     installed and PETSc must be configured to use CUDA. See the PyLith
     manual and PETSc documentation for details.

   * User-specified start time for simulations.

     Users can set the simulation start time to any desired value. This
     facilitates combining simulations to model the earthquake cycle.

   * Elastic prestep in quasi-static simulations is optional.

     The elastic prestep in quasi-static simulations can be skipped
     (the default is to include the elastic prestep). This facilitates
     combining simulations to model the earthquake cycle.