[CIG-SHORT] PyLith 1.6.1 bugfix release now available

[Brad Aagaard]

Greetings,

I am pleased to announce the release of PyLith 1.6.1, a finite-element
code designed to solve dynamic elastic problems and quasi-static
viscoelastic problems in tectonic deformation.

This release fixes a few bugs in PyLith v1.6.0 and includes small
updates to the manual and examples. We strongly recommend all users of
previous PyLith releases switch to this latest release.

   IMPORTANT NOTE:

     Version 1.6.1 imposes stricter requirements on descriptive labels
     for spatial databases and friction models. In previous versions
     the default values (empty strings) were allowed. Users are now
     required to specify these values as empty strings are no longer
     allowed. This results in much better error messages.


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

* Validation of user input

   Added stricter requirements for descriptive labels of various
   objects, including spatial databases and friction models. The
   default labels are empty strings which do not result in useful error
   messages; the user is now required to specify a non-empty string for
   the labels. This makes errors related to spatial databases much
   easier to diagnose.


* Updates to manual

   - Updated description of cell_info_fields for Neumann boundary
     condition. The description had not been updated to reflect the
     time-dependence introduced in version 1.4.

   - Added steps 18 and 19 that discuss time-dependent Neumann boundary
     conditions to examples/3d/hex8.


* Bug fixes

   - Fixed bug in writing rupture information to VTK and HDF5 files
     when using multiple earthquake sources. Field names did not include
     name of rupture. This caused loss of information in VTK output and
     a corrupted Xdmf metadata file for HDF5 output.

   - Fixed error in use of initial stress tensor with generalized Maxwell
     models. The initial stress tensor was added to the current stress
     tensor twice.

   - Fixed two bugs in the fault friction implementation. One bug
     pertained to accounting for roundoff errors and convergence
     tolerances in computing the slip rate. Slip rates less than
     1.0e-12 (nondimensionalized) are set to zero. The friction
     implementation for quasi-static problems contained a bug that
     resulted in slip extending over all of the fault rather than the
     appropriate isolated patch.

   - Cleaned up Green's function example (examples/greensfns/hex8) so
     that it runs without errors. Eliminated extraneous processing.

   - Cleaned up meshing examples (examples/meshing), including
     elimination of superfluous pre-processing.

   - Adjusted absolute tolerances for PETSc solves in examples/3d/hex8
     so that solver terminates with desired convergence criterion.

   - Updated examples/2d/subduction/geometry.jou to use APREPRO
     functions and variables to store id values.