Lesson 6 : Using Data Parameter File

We present here an example of use of the Parameter Data File. This powerful tool simplifies for a user the introduction of input data specific to OFELI. The idea is very simple : you have to write a text file following some simple rules and declare, in your code, an instance of class IPF. Each parameter introduced in your file is then recovered from a specific member function from your instance. We shall illustrate hereafter this through an example of a fluid flow code. Note that a precise description of the input file can be found in this page.

An Input Data File

#PARAM!
# Cavity test
Proj        test
MaxTime      1000
TimeStep    0.01
Verbose        1
Output         0
Save           0
Tolerance  1.e-5
Plot        1000
Init           1
DoublePar      1    # Density
DoublePar   0.0001  # Viscosity
MeshFile     test.m
AuxFile      test.v
AuxFile      test.sav
EOF

Let us make some comments about the structure of this file:

• A parameter file must start (first line, first column) by the string #PARAM!
• Comments are introduced between the character # and the end of a line.
• We give a project name through the keyword Proj. All input and output files will then have, by default, this project name as a prefix, the extension depending on the nature of the file.
• An input parameter file contains two types of data: parameters which are integer and double precision numbers and file names. There are some predefined parameters and file names, all the others must be given under a generic keyword. For example : MaxTime, TimeStep, Verbose, ... are predefined parameters.
• The last line of the file must be EOF.

   IPF data(argv[1]);
   double max_time = data.getMaxTime();
   double deltat = data.getTimeStep();
   int verbose = data.getVerbose();
   int output_flag = data.getOutput();
   int save_flag = data.getSave();
   double tol = data.getTolerance();
   int plot_flag = data.getPlot();
   double dens = data.getDoublePar(1);
   double visc = data.getDoublePar(2);
   ms.Get(data.getMeshFile());
   FDF vf(data.getAuxFile(1),"w");
   FDF sf(data.getAuxFile(2),"w");
   int init_flag = data.getInit();