[CIG-ALL] PyLith 1.5.2 bugfix release

[Brad Aagaard]

Greetings,

I am pleased to announce the release of PyLith 1.5.2, a finite-element
code designed to solve dynamic elastic problems and quasi-static
viscoelastic problems in tectonic deformation.

This release fixes several bugs in v1.5.1. We strongly recommend
all users of previous PyLith releases to switch to this latest
release. See the README file for changes required to switch to the
v1.5.x release series from previous versions.

You can download the source code and binaries from

     http://www.geodynamics.org/cig/software/pylith

Detailed installation instructions are in the User Manual with example
installation procedures for a few platforms in the bundled doc/install
directory.


RELEASE NOTES

   * PyLith 1.5.2 requires FIAT version 0.9.9 or later and an updated
     PETSc development version. It also requires users to update to the
     latest spatialdata version for compatibility of the SWIG generated
     files. These are included in the binary distribution, but users
     building PyLith from source will need to update FIAT, PETSc, and
     spatialdata.

   * Users of the Darwin 10.6 binary version must have /usr/bin/python
     as the Python interpreter in their path. You can verify this by
     running "which python".

   * Bug fixes

     - Fixed setting of elastic constants in DruckerPrager3D and
       computation of the yield function. Some off-diagonal elasticity
       constants were off by a factor of 2.0 and the yield function was
       missing a factor of 0.5 and sqrt().

     - Fixed computation of stable time step when using initial
       stresses with PowerLaw3D. If effective stress is zero, then
       stable time step is infinite.

     - Re-enabled check for compatibility of quadrature scheme and
       cells for bulk rheologies.

     - Added check to configure for compatible version of FIAT.

     - Fixed bug where buffer for output of initial stresses for
       dynamic (spontaneous) rupture.


Version 1.6

We plan to release version 1.6.0 in early June. Version 1.6 will include 
parallel, binary output via HDF5, uniform global refinement, automatic 
numerical damping via viscosity for explicit time-stepping simulations, 
and integration of a PETSc algebgraic multi-grid solver with a custom 
fault preconditioner.

Regards,
Brad Aagaard, Charles Williams, Matthew Knepley