Special Parameters and Attributes

There are several ``special'' parameters defined by RNPL These are declared by the program (if not by the user) and given default values. They will be read from the parameter file if it contains them. These parameters are shown in the following list along with their definitions and default values.

constant parameter float start_t := 0 // start time
constant parameter int iter := 100 // number of iterations
constant parameter float epsiter := 1e-5 // iteration threshold
constant parameter int fout := 0  // file output (0 no, 1 yes)
constant parameter int ser := 0 // fs output (0 no, 1 yes) if appropriate
constant parameter float lambda := .5 // dt/dr, dr=sqrt((dx^2+dy^2+dz^2)/3)
constant parameter int rmod := 1 // output every rmodth time step
constant parameter string in_file // name of file from which initial data 
                                  // will be read
constant parameter string out_file // name of file to which data will 
                                   // be written
constant parameter int level := 0 // refinement level
constant parameter int s_step := 0 // starting iteration number
constant parameter string tag := "" // prepend symbol for grid function names
constant parameter int N<c>0 := 2 // base number of grid points for the 
                                // coordinate c (there is one for each spatial 
                                // coordinate)

The names N<c> , where <c> is a coordinate, are declared internally to RNPL . They are NOT parameters, nor should they be declared by the user. N<c> is defined at run time by . Thus, if a grid is defined with an index region of length N<c> , it will be automatically scaled simply by changing the value of level in the parameter file. Grids defined in this way will always have an odd number of points in each dimension.

There is one pre-defined attribute: out_gf. This is an integer array with one element for each grid function, that is:

attribute int out_gf encodeone

Each element is assigned the default value of 0. This element tells whether output is enabled for that grid function or not. The values of this attribute can be changed during program execution.