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DUNE-ALUGrid module
===================

License
-------

The DUNE-ALUGrid module is licensed under the GNU General
Public License (GPL) version 2. The full license text can be found 
in the file COPYING and via http://www.gnu.org/licenses/gpl.html .


Compiler 
--------

The DUNE-ALUGrid code is known to compile with the GNU Compiler version 4.6.x or higher. 
The code also compiles with the INTEL C++ Compiler (tested version 13.1).

The compiler can be chosen by setting the variable CXX correctly, i.e. 
CXX=g++ or CXX=icpc. Please see the documentation of the DUNE build system.


Dynamic Load Balancing Options
------------------------------

If the compiled code is used for parallel computations including dynamic
load balancing, then a parameter file named "alugrid.cfg" should be
available in the directory the program is launched. See
"misc/alugrid.cfg" for an example file. 

The file must contain three values: 
first row:  ldb_under (value < 1.0),  default value is 0.0
second row: ldb_over (value > 1.0),   default value is 1.2 
third row: Graph partitioning method, default method is 4 (METIS_PartGraphKway)

Available methods are: 

NONE = 0
COLLECT = 1 (collect all elements to process 0)

ALUGRID_SpaceFillingCurveLinkage       = 4
ALUGRID_SpaceFillingCurveSerialLinkage = 5

ALUGRID_SpaceFillingCurve       = 9  (default)
ALUGRID_SpaceFillingCurveSerial = 10

METIS_PartGraphKway        = 11
METIS_PartGraphRecursive   = 12

ZOLTAN_LB_HSFC  = 13
ZOLTAN_LB_GRAPH = 14
ZOLTAN_PARMETIS = 15

See the documentation of the corresponding package for detail on the
methods. 


Debug Options
--------------

There are several debug options that can be set an shell environment
variable and that forces the code to produce debug output. To use this
feature, the code must be compiled without the CPP variable NDEBUG set. 
The following shell environment variables can be set to a level of 
verbosity (higher is better).

VERBOSE      general verbose output  
VERBOSE_MGB  output produced by the macro grid builder 
VERBOSE_LDB  output produced while partitioning. 
VERBOSE_PLL  output produced by parallel grid methods


Optimization 
-------------

The DUNE-ALUGrid code is highly riddled with assert statements. 
Therefore it is recommended to compile the library and the application code
with the CPP variable NDEBUG set (i.e. -DNDEBUG) to avoid all asserts
statement tests. 


Debug
-----

For debugging the code the preprocessor variable NDEBUG must not be defined
and additionally the preprocessor variable DEBUG_ALUGRID can be defined
for object reference counting. In the read method of the message
buffer for parallel computations a eof check is done on every read
which can be disabled by passing the preprocessor variable
NO_OBJECTSTREAM_DEBUG.


Knowns Bugs 
-----------

- Ghost elements do not work for tetrahedral grid when using bisection refinement.