private static void diffusivity_2d_elman_contour()
//****************************************************************************80
//
// Purpose:
//
// diffusivity_2d_elman_contour displays a contour plot of a 2D stochastic diffusivity function.
//
// Discussion:
//
// The diffusivity function is computed by DIFFUSIVITY_2D_ELMAN.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 07 August 2013
//
// Author:
//
// John Burkardt
//
// Reference:
//
// Howard Elman, Darran Furnaval,
// Solving the stochastic steady-state diffusion problem using multigrid,
// IMA Journal on Numerical Analysis,
// Volume 27, Number 4, 2007, pages 675-688.
//
{
string command_filename = "diffusivity_2d_elman_commands.txt";
List <string> command_unit = new();
string data_filename = "diffusivity_2d_elman_data.txt";
List <string> data_unit = new();
int m_1d = 5;
int nx = 51;
int ny = 51;
Console.WriteLine("");
Console.WriteLine("diffusivity_2d_elman_contour");
Console.WriteLine(" Display contour or surface plots of the stochastic");
Console.WriteLine(" diffusivity function defined by diffusivity_2d_elman.");
//
// Set the spatial grid.
//
double a = 1.0;
double[] xvec = typeMethods.r8vec_linspace_new(nx, -a, a);
double[] yvec = typeMethods.r8vec_linspace_new(ny, -a, a);
double[] xmat = new double[nx * ny];
double[] ymat = new double[nx * ny];
typeMethods.r8vec_mesh_2d(nx, ny, xvec, yvec, ref xmat, ref ymat);
//
// Sample OMEGA.
//
int seed = 123456789;
typeMethods.r8vecNormalData data = new();
double[] omega = typeMethods.r8vec_normal_01_new(m_1d * m_1d, ref data, ref seed);
//
// Compute the diffusivity field.
//
double cl = 0.1;
double dc0 = 10.0;
double[] dc = Stochastic.diffusivity_2d_elman(a, cl, dc0, m_1d, omega, nx, nx, xmat, ymat);
//
// Create a data file.
//
for (int j = 0; j < ny; j++)
{
for (int i = 0; i < nx; i++)
{
data_unit.Add(" " + xmat[i + j * nx].ToString(CultureInfo.InvariantCulture).PadLeft(14)
+ " " + ymat[i + j * nx].ToString(CultureInfo.InvariantCulture).PadLeft(14)
+ " " + dc[i + j * nx].ToString(CultureInfo.InvariantCulture).PadLeft(14));
}
}
File.WriteAllLines(data_filename, data_unit);
Console.WriteLine("");
Console.WriteLine(" Created graphics data file '" + data_filename + "'");
//
// Create the command file.
//
command_unit.Add("# " + command_filename + "");
command_unit.Add("#");
command_unit.Add("# Usage:");
command_unit.Add("# gnuplot < " + command_filename + "");
command_unit.Add("#");
command_unit.Add("set term png");
command_unit.Add("set output 'diffusivity_2d_elman.png'");
command_unit.Add("set xlabel '<---X--->'");
command_unit.Add("set ylabel '<---Y--->'");
command_unit.Add("set zlabel '<---DC(X,Y)--->'");
command_unit.Add("set title 'Elman Stochastic diffusivity function'");
command_unit.Add("set contour");
command_unit.Add("set timestamp");
command_unit.Add("set cntrparam levels 10");
command_unit.Add("#set view map");
command_unit.Add("set view 75, 75");
command_unit.Add("unset key");
command_unit.Add("splot '" + data_filename + "'");
File.WriteAllLines(command_filename, command_unit);
Console.WriteLine(" Created graphics command file '" + command_filename + "'");
}
