ChangeLog

Notation: *+ fixed bug
	  ++ new feature
          o+ optimization
	   + minor modifications

Tracker IDs at SourceForge.net:
BR xxxxxxx : Bug Reports 
FR xxxxxxx : Feature Requests 
SR xxxxxxx : Support Requests


-- v 2.3.9
++ attenuation with constant Q
++ anisotropy in SH waves (FR 3547982)
 + dynamic faults can open with free stress
 + meshes without boundary conditions are allowed
 + bottom boundary can be split
*+ in slip-strengthening faults, mu was incorrectly =mus (pointed out by Yihe Huang)
*+ corrected meaning of mus and mud in exponential slip-weakening friction 
*+ unassociated pointers (BR 4)
*+ fixed handling of splines for layered mesh


Tue Aug  7 15:21:11 PDT 2012 -- v 2.3.8
 ++ mesh2d/read_inp.m reads mesh in ABAQUS' INP format exported by CUBIT 
    (http://cubit.sandia.gov)
 ++ mesh2d/read_dcm.m reads mesh in DCM format exported by EZ4U
    (http://www-lacan.upc.es/ez4u.htm)
 ++ preliminary version of kinematic fault sources (new &BC_KINFLT block)
 ++ heterogeneous coefficients for anisotropic media 
    FR 3313940
  + PRE/critical_timestep.m computes the critical time step for given element
    size and NGLL
  + &BC_DTTTN0 removed (superseded by &BC_DIRNEU and &BC_KINFLT)
  + absorbing boundaries with arbitrary orientation
    (but only with explicit scheme, no Stacey, not periodic, no incident waves)
  + warning when a declared material is not used by any element
  + Gaussian source time function (&STF_GAUSSIAN)
 *+ time-weakening does not override stopping barriers in slip-weakening anymore
 *+ time-weakening does not impede healing of rate-and-state friction anymore
 *+ fixed segmentation fault during initialization of pure time-weakening friction
 *+ fixed handling of tip nodes of single-sided faults
  

Wed Aug 11 23:40:29 PDT 2010 -- v 2.3.7 
(released in SourceForge on Aug 3 2012)
 ++ more stable curved elements (Q8h) for faults with smooth normal 
    (new option ztopH='CSPLINE' in &MESH_LAYER and new &CSPLINE block)
 ++ added cohesion to dynamic faults (parameter 'cohesion' in &BC_DYNFLT)
 ++ new option 'kind' in &BC_DYNFLT_TWF selects the type of time-weakening 
    space-time distribution. With kind=2 the expansion of the weakening front is 
    followed by contraction of a healing front, as in Andrews and Ben-Zion (1997, eqs 2-3).
  + dynamic faults now ignore crack-tip (non-split) nodes
  + in &DIST_LINEAR and &DIST_SPLINE the input does not need to be ordered anymore
  + enabled time-weakening in combination with rate-and-state-dependent friction
  + new parameter 'fznz' in &MESH_CART and &MESH_LAYERED sets the thickness of 
    the fault zone layer
  + in &GENERAL, the new default is fmax=1 Hz
  + added flexibility to mesh2d:
    mesh2d_merge now allows for non consecutive boundary tags
    and number of sides different than 4,
    mesh2d_wedge now allows for curved boundaries and prescribed boundary nodes
 *+ fixed bug with &BC_DIRNEU in SH mode (ndof=1)
 *+ in &BC_DYNFLT_TWF (kind=1) the final time-weakening front is now exactly at V*T


Tue Sep  1 15:24:18 PDT 2009 -- v 2.3.6
 ++ mesh generation for faults with smooth normal vector 
    (new &QSPLINE block and new option ztopH='QSPLINE' in &MESH_LAYER)
 ++ instantaneous healing for slip-weakening friction 
    (new parameter 'healing' in &BC_DYNFLT_SWF)
  + optional fault opening instead of tensile normal stress
    (new parameter 'opening' in &BC_DYNFLT, turned on by default as in earlier versions)
  + easy tagging of near-fault elements during mesh generation to set a 
    damping zone (new parameter 'fztag' in &MESH_LAYERED and &MESH_CART)
  + initial values of fault stresses and friction (Tt,Tn,mu) 
    exported to file FltXX_init_sem2d.tab
  + added cohesion-like normal response to dynamic faults
    (kind=0 in &BC_DYNFLT_NOR)
  + initial plastic strain is now always zero (removed 'ep' from &MAT_PLASTIC)
 *+ fixed bug with plastic solver in version 2.3.5 (pointed out by Shiqing Xu)
 *+ fixed bug in the computation of elastic energy in plastic materials
 *+ damage stress glut set to zero for plastic and elastic materials
 *+ pointers initialized to null to fix problem with gfortran compiler
 *+ fixed path to file gll_sem2d.tab in POST/sem2d_read_specgrid.m

Mon Feb 16 13:29:15 PST 2009 -- v 2.3.5
 ++ Matlab tools to generate structured meshes (see PRE/mesh2d)
 ++ new mesh database input format (see MESH_MESH2D and EXAMPLES/Using_MESH2D)
 ++ compute and export stress glut of materials with plasticity or damage 
    (see parameter COMPUTE_STRESS_GLUT in constants.f90)
 ++ compute and export seismic potency of dynamic faults
 ++ new post-processing Matlab functions:
    sem2d_plot_grid, sem2d_snapshot_movie 
  + SRC_DEF block: extended format of input file to allow different amplitude
    for each source
  + DIST_LINEAR and DIST_SPLINE now work along X or Z
  + the SRC_FORCE block is not required anymore in SH mode (ndof=1)
  + if a boundary tag declared in a BC_DEF block is not present in the mesh
    the code ignores the boundary condition, instead of aborting
  + PRE/ViewMeshQuality.m is now a function, conversion to log-index is
    optional, it runs faster and is better documented
  + POST/sem2d_read_fault.m has new default filename
  + POST/plot_seis.m now has an amplitude scaling factor
  + the user's guide was reorganized
 *+ elastic and plastic energies are now computed correctly in plastic materials
 *+ Brune source now is properly set to zero at negative times
 *+ Arias intensity function now deals properly with leading zeros

Wed Nov 26 18:38:29 PST 2008 -- v 2.3.4
  + Brune's source time function (STF_BRUNE)
  + energy outputs: change of elastic energy, kinetic energy, energy dissipated by plasticity
    (expert parameter COMPUTE_ENERGIES in constant.f90)
  + divergence and curl of velocity added to snapshot outputs (fields='d' or 'c' in SNAP_DEF)
  + export displacements and velocities of each side of the fault 
    (new parameter osides in BC_DYNFLT)
  + updated and added more post-processing tools: spec2D_cplot, arias_intensity, 
    response_spectrum, sem2d_extract_line, sem2d_extract_points, plot_model
 *+ STF_TAB now assumes values beyond input time range are same as initial or final times
 *+ fixed interpolation problem in DIST_HETE1 
 *+ fixed plotting of velocity model as background in SNAP_PS

Tue Aug  5 18:03:42 PDT 2008 -- v 2.3.3
 ++ Maxwell visco-plasticity (new parameter Tv in MAT_PLAST)
 ++ Non planar faults meshes (new parameter ezflt in MESH_LAYER)
  + Horizontal fault at arbitrary vertical position 
    (new parameter ezflt in MESH_CARTESIAN, supersedes FaultX)
  + DIST_LINEAR can now read data from Par.inp
 *+ Fixed a bug in initialization of Newmark parameters, by separating
    Newmark and HHT-alpha schemes in two different input blocks, 
    TIME_NEWMARK and TIME_HHTA respectively
 *+ Fixed syntax of REC_LINE: 'number' is no longer required when using 'file'
 
Fri May 16 16:20:02 PDT 2008 -- v2.3.2
 
 ++ velocity and state dependent friction law,
    as in Ampuero and Ben-Zion (GJI, 2008)
    See EXAMPLES/Velocity_weakening
 *+ time-weakening (BC_DYNFLT_TWF) was only enabled with slip-weakening
    (BC_DYNFLT_SWF), now it can stand alone too
 *+ fixed memory report for very large simulations
 
Wed Apr  9 20:58:29 CEST 2008 -- v2.3.1

 ++ time weakening friction at prescribed rupture speed,
    possibly cobined with other friction laws for initiation
    (see BC_DYNFLT_TWF)
 o+ refactoring to reduce memory overhead
  + encapsulation of material modules
  + improved CPU time and memory usage estimates 
  + avoid stack overflow in unformatted direct access writes
 *+ fixed a memory leak during cleanup of linked lists

Thu Mar  6 18:11:49 JST 2008 -- v2.3.0

 ++ continuum damage (see MAT_DMG)
 ++ Coulomb plasticity (see MAT_PLAST)
 ++ normal stress response regularization for bimaterial faults 
    (see BC_DYNFLT_NORMAL block and EXAMPLES/Bimaterial_fault)
 ++ major refactoring, more commented code and guidelines for programmers in documentation
    allow easier implementation of new materials, source time functions,
    distributions and boundary conditions
 ++ Dirichlet and Neumann boundary conditions (see BC_DIRNEU block, supersedes BC_DT0TN0)
 ++ export triangulation file for GMT's "pscontour -T" (see PLOTS block)
 ++ monochromatic source time function (see STF_HARMONIC)
 ++ linear slip fault also for SH waves (see BC_LSF)
 ++ more and better documented Matlab utilities for plotting outputs, 
    including a GUI for snapshot views (see POST/*.m)
  + improved documentation
  + the syntax of the following input blocks has changed: 
    MATERIAL, SNAP_DEF (renamed PLOTS), SNAP_PS (renamed PLOTS_POSTSCRIPT), 
    DIST_GAUSSIAN, BC_ABSO, BC_DYNFLT (renamed BC_SWFFLT), GENERAL and SRC_DEF. 
    (ECHO block was removed) 
  + KELVIN_VOIGT block renamed, new name is MAT_KV
  + ELASTIC block renamed, new name is MAT_ELAST
 *+ fixed writing of file MeshNodesCoord_sem2d.tab
 *+ fixed reference point in wave sources with incidence from above
 *+ fixed postscript plotting with interpolation
    SR 1746891
 o+ more memory optimizations for box grids with homogeneous materials
 o+ optimized matrix products
 

Wed Jun  6 17:32:34 CEST 2007 -- v2.2.11

 *+ fixed obliquely incident plane waves (see SRC_WAVE input block)
    FR 1676280
 ++ moment tensor sources (see new SRC_DOUBLE_COUPLE and SRC_MOMENT input blocks)
 ++ source time function interpolated (spline) from a user supplied file
  + allow source locations at interelement nodes
  + SRC_RICKER input block name changed to STF_RICKER
  + argument "Periodic" deleted from BC_XXX blocks (now handled internally)
  + interpolation of scalar snapshot plots
  + POST/movie.csh now crops the figure only upon request (-crop option)

Fri Jun  1 00:21:22 CEST 2007 -- v2.2.10
 ++ built-in mesh generation for layered medium
    possibly with surface and sub-surface topography
    See MESH_LAYERED input block
    See also PRE/set_mesh_layers.m, EXAMPLES/TestLayers and 
    EXAMPLES/TestLayers_2
 ++ scripts POST/read_seis.m and POST/plot_seis.m to read
    and plot seismogram outputs on Matlab
 ++ script for automated tests EXAMPLES/run_tests.csh
 *+ fixed intent(in) bug and handling of Q9 elements
    in fem_grid.f90 (FE_SetConnectivity)
 *+ fixed array allocation bug in spline_dist.f90
 o+ optimization settings in module constants.f90
    should be modified by user before compilation
  + file format changed in DIST_SPLINE, DIST_LINEAR, 
    DIST_GRADIENT, REC_LINE and SRC_DEF :
    the first line (which used to contain the number of data lines)
    is not needed anymore

Wed Apr  4 10:21:55 CEST 2007 -- v2.2.9
 *+ fixed reading of HETE_DIST1 input block
    and more robust interpolation at the edges
    BR 1692766
 ++ template for user-supplied source time function (src_user.f90)
    See SRC_USER input block
    FR 1691682
  + new example "LambsProblem", as in Mercerat et al. (2006)
    SR 1681080

Mon Mar 12 05:06:31 CET 2007 -- v2.2.8
 ++ receivers can be located at arbitrary positions, read from a file, 
    not necesarily at computational nodes. See the REC_LINE block
    FR 1639079
 ++ multiple sources, with location and delay-time read from a file.
    See SRC_DEF block
    FR 1675299

Thu Feb  8 16:52:09 CET 2007 -- v2.2.7
 ++ materials can have heterogeneous distributions using DIST_XXXXX blocks
    (see EXAMPLE/InaBox)
    SR 1631862
 ++ new DIST_HETE1 interpolates linearly from a regular grid (see EXAMPLE/InaBox)
 *+ fixed bug when writing "Stability_sem2d.tab"
  + added a FAQ to the user's guide
    SR 1653849 1648483

Thu Jan 18 16:21:36 CET 2007 -- v2.2.6
  + Kelvin-Voigt viscosity: fixed wrong format in initialization outputs
  + PRE/ViewMeshQuality.m: modified, see user's guide section 2.4
  + EXAMPLES/TestFlt1D/ : corrected Par.inp

Wed Nov  1 22:45:39 CET 2006 -- v2.2.5
 ++ symplectic time-stepping algorithms, PFR and PEFRL (4th order)
 o+ Reverse Cuthill-McKee element reordering
  + PostScript snapshots for each component in P-SV
 *+ abort if undefined boundary tag
 *+ first sample in seismograms is t=0
 *+ added Kelvin-Voigt to Newmark solver

Wed Jan 18 10:51:01 CET 2006 -- v2.2.4a
 *+ Kelvin-Voigt routines fixed for g95 compiler

Mon Aug 22 22:55:56 CEST 2005 -- v2.2.4
 ++ SH waves (anti-plane, scalar wave equation), see "ndof=1" in &GENERAL 
 ++ leapfrog (staggered centered-difference) is now the default time scheme
    It is faster, uses less memory and allows accurate explicit treatment
    of dynamic fault boundaries (see "kind" in &TIME)
 ++ Kelvin-Voigt material, only with leapfrog (see &KELVIN_VOIGT)
 ++ bc_abso: new implementation, absorbing boundaries are now second order in dt
 *+ faults: mapping to the fault coordinate system was handled incorrectly
    (this bug might have corrupted curved faults in P-SV)
 *+ time scheme: consistent check for stability in dissipative schemes
 o+ faster initialization (changed the node numbering algorithm)
 o+ optimization: up to 50% performance gain by declaring NGLL as parameter 
    in core subroutines (ELAST_KD). Before compiling, the user must edit elastic.f90
    setting OPT_NGLL to a frequent value.
 o+ memory optimization: jacobian and local weights not stored
  + faults: input initial tractions renamed + new input initial stress 
  + outputs: PostScript snapshots of color scalar fields 
    (set "vector=F, color=T" in PLOT_POSTSCRIPT) 
  + post: sem2d_view.m for Matlab
  + post: "Snapshot_*.ps" renamed to "x_*.ps" where x=d,v or a.

Mon Feb  7 23:38:44 CET 2005 -- v2.2.3
  + outputs: binary formats, see "bin" option in PLOTS
             field selector "fields"
             stress and strain outputs
  + pre- and post-process: tools for visualization under gnuplot and Matlab,
	for conversion of output to ascii (see PRE/ and POST/)
  + post: movie.csh runs now with animate (ImageMagick) instead of xanim
        and gifsicle instead of gifmerge
  + doc: more about the method, mesh verification, output formats 
 *+ bc_swfflt: NSAMP in output header file was inaccurate
 *+ mesh_cartesian, mesh_emc2 and init: bugs higlighted by g95 compiler (G.Wimpey)

lun Aug 9 20:15:09 EDT 2004 -- v2.2.2
 *+ Intel fixed their bug in the "transfer" intrinsic,
    the code now works with Intel compiler ifort, version 8.0.046_pe047.1
 *+ fixed bug in the numbering algorithm
  + fixed POST/movie.csh

jeu nov 13 20:02:09 EST 2003 -- v2.2.1
 *+ emc2, cracks and faults: bug fixed in the handling of crack tip nodes.
    As a new convention, crack tip nodes must be assigned a special tag: -1.

mar oct 28 17:08:10 EST 2003 -- v2.2
 ++ boundary conditions: new kind BC_SWFFLT, slip weakening fault
 *+ boundary conditions: bug fixed in the numbering subroutine
  + seismograms: fixed the scripts (don't need ShowSeis_sem2d.csh anymore)
  + time scheme: parameterized dissipation in explicit Newmark-alpha
 o+ solver: optimized for memory
  + distributions: new kind PWCONR 

jeu oct 23 15:13:48 EDT 2003 -- v2.1beta
 ++ new boundary condition: linear slip fault (BC_LISFLT input block)
  + "Periodic" flag in BC_ABSORB
  + doc: explanation of seismograms data format

lun oct 13 19:58:59 EDT 2003 -- v2.0