Parameters in `commons'

The parameters in the file commons are parameters in the sense of the FORTRAN parameter statement. Most of them are used for setting array dimensions. These all appear near the top of commons, and are changed by editing the file commons. The total number of words of memory used is approximately

where r is ndord and v is ndvert.

integer ndvert

is the maximum number of vertices in the grid. This is the most important parameter concerning the amount of memory required. Default: 1000

integer ndlev

is the maximum number of levels for the adaptive refinement procedure.
Default: 40

integer ndord

is the maximum polynomial order allowed. In the current version of MGGHAT there is no reason to have this larger than 4. If you know you will only be using, for example, the second order method (linear elements, specified by iorder=2), then setting ndord=2 will substantially reduce the memory requirements. Default: 4

integer ndsave

is the maximum number of refinement steps that will be saved for gnuplot convergence files. It has very little effect on memory usage, and the current setting of 100 should be sufficient. Default: 100

integer ndrow0 and ndband

are memory allocations for the band matrix storage form of the matrix from the initial grid. ndrow0 should be as large as the number of nodes in the initial grid, which is bounded by where r is the polynomial order (specified by iorder) and is the number of vertices in the initial grid. ndband is difficult to estimate for an arbitrary initial triangulation. It depends on the way the vertices are ordered and the polynomial order. For the sample rectangular domain in the example user.f files, it is bounded by , where ngridy is defined in the sample subroutine inittr. If the values you supply are not large enough, you will get an error message at run time informing you how large they should be. Default: ndrow0=100, ndband=48

character tmpdir

is the only parameter not used for dimensioning. This is the name of a directory in which to write temporary files with messages passed between mgghat and the widget--based menu for graphics. It is recommended that this directory be on a local disk, not on a remote disk served by the network file server, to avoid overloading the network. If you change it, make sure you also change the declaration character*5 to have enough characters for the directory name. Default: /tmp/