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.


