-general : Annotations, filenames

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 # outfile    = /tmp/--username--/--SomeDirectory--/Results                   #
 # scratchbase= /tmp/--username--/--SomeDirectory--/scratch                   #
 # restartfiles= -none-                                                       #
 #   t1restartfiles=  1440         -- Minutes. When to write the first set.   #
 #   dtrestartfiles=  1440         -- Minutes. Distance between writing.      #
 #   stopafterrestartfiles=1000000000   -- Stop after writing so often.       #
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 # dice  = yes                -- PVM/MPI: use many subvolumes                 #
 # ndpw  = auto               -- PVM/MPI: number of dice per worker           #
 # iodice= no                 -- PVM    : each worker writes its own results  #
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• outfile The name of the file^1.1 where the solutions shall be stored in. This file may exist. If it exists, then its content will be overwritten.
• scratchbase The base name of scratchfiles that gd1 needs for its operation. If you have an environment variable TMPDIR set, gd1 will as default set scratchbase to the string

          $TMPDIR/gdfidl-scratch-pid=XXXXX-
  

  Here $TMPDIR is the value of the environment variable TMPDIR, and XXXXX is the numerical value of the process-id of gd1.
• restartfiles This is for preparing a long running computation to survive a system crash. The value to give for restartfiles must be a valid filename, in a filsystem which survives a system crash, ie. a filesystem which is not cleared at boot time. If a value for restartfiles is given the solver will write a set of at selected times. There will be up to two sets of restartfiles. There are two sets because according to murphy's law it will happen that a system crash just occurs while one set is being written. In such a case, the older set can still be used. When the restartfiles are written, a comment is given how to use the restartfiles. Essentially it is: you have to restart the computation on the same computer system (If using a parallel system: with the same number of tasks, using the same nodes, using the same executable), with an additional parameter on the command line of the master task. The additional command line parameter is -restartfiles=NAME-OF-SET .
• t1restartfiles First time (in minutes) to write restartfiles.
• dtrestartfiles Time difference (in minutes) between the times when to write restartfiles.
• stopafterrestartfiles Number of restartfile sets to write. After that set of restartfiles has been written, the computation will stop.
• text(*)= This annotation text is plotted together with the field plots. This is especially useful for documenting the geometry parameters of a calculation.
  syntax:
  text()= ANY STRING, NOT NECESSARILY QUOTED
  or
  text(NUMBER)= ANY STRING, NOT NECESSARILY QUOTED
  
  
  
  • ANY STRING, NOT NECESSARILY QUOTED:
    The string to be included in the plots,
  • NUMBER:
    Optionally, the line number, where the text should be plotted.
  In the first case, without NUMBER, the string following text()= is placed in the next free line. In the case with NUMBER, it is guaranteed, that the string is placed in the NUMBER.st line. You can specify up to 20 annotation strings, the maximum length of each annotation string is 80 characters.
• dice= [yes|no] When computing in parallel, and dice= yes, the computational volume is subdivided in many more subvolumes than available processors. This leads to a better loadbalancing.
• ndpw= [auto|NUMBER] When computing in parallel, and dice= yes, the computational volume is subdivided in NUMBER subvolumes per processor. If ndpw=auto, the number of subvolumes (dice) is chosen such that each subvolumes contains about 1 million gridcells.
• iodice= [yes|no] When computing in parallel, and dice= yes, the results of each subvolume is stored on the local disk of each processor. This leads to faster writing of the results, but longer time for postprocessing of the results.

  This might be needed for very large parallel computations where the computed electromagnetic fields must be loaded into the postprocessor for computing eg. the Q-value. For very large parallel computations, it can happen that the computed datasets are so large that the postprocessor cannot handle the amount of data in its limited adress space (32 bit processors). When dice= yes, iodice= yes, the results are written to the local disks of the compute nodes, and when the results shall be analysed by gd1.pp, on each compute node an instance of gd1.pp will be running, handling the local amount of data.

  Only the PVM version of gd1.pp can be run in parallel. There is no MPI version of gd1.pp, as MPI lacks some needed functionality.

Example The following specifies that the results of the computation shall be stored in the database with name '/tmp/UserName/resultdirectory'. The names of scratchfiles that gd1 generates shall start with '/tmp/UserName/delete-me-'. Restartfiles shall be written every 24 hours, and the names of the restartfiles shall start with
/tmp/UserName/restartfile. Together with the plots that gd1.pp will produce, the strings 'Parameter is 45' and '2*Parameter is 90' shall appear.

 -general
     outfile= /tmp/UserName/resultdirectory
     scratch= /tmp/UserName/delete-me-
     restartfiles= /tmp/UserName/restartfile

 define(PARAMETER, 45)
     text(1)= Parameter is PARAMETER
     text(2)= 2*Parameter is eval(2*PARAMETER)

Footnotes

... file^1.1

This will actually be a directory. The reason is: For current (2009) workstations, it is quite easy to generate data in excess of 2GBytes. But many current filesystems and OS-tools cannot handle files larger than 2GBytes. So we chose to organise the computed data as a hierarchy of files. A directory is a hierarchy of files, so we used just that.