private static void Main(string[] args)
//****************************************************************************80
//
// Purpose:
//
// MAIN is the main program for PATTERSON_RULE.
//
// Discussion:
//
// This program computes a standard Gauss-Patterson quadrature rule
// and writes it to a file.
//
// Usage:
//
// patterson_rule order a b output
//
// where
//
// * ORDER is the number of points in the rule, and must be
// 1, 3, 7, 15, 31, 63, 127, 255 or 511.
// * A is the left endpoint;
// * B is the right endpoint;
// * FILENAME is the "root name" of the output files.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 21 February 2010
//
// Author:
//
// John Burkardt
//
{
double a;
double b;
string filename;
int order;
Console.WriteLine("");
Console.WriteLine("PATTERSON_RULE");
Console.WriteLine("");
Console.WriteLine(" Compute a Gauss-Patterson rule for approximating");
Console.WriteLine(" Integral ( -1 <= x <= +1 ) f(x) dx");
Console.WriteLine(" of order ORDER.");
Console.WriteLine("");
Console.WriteLine(" The user specifies ORDER, A, B, and FILENAME.");
Console.WriteLine("");
Console.WriteLine(" ORDER is 1, 3, 7, 15, 31, 63, 127, 255 or 511.");
Console.WriteLine(" A is the left endpoint.");
Console.WriteLine(" B is the right endpoint.");
Console.WriteLine(" FILENAME is used to generate 3 files:");
Console.WriteLine(" filename_w.txt - the weight file");
Console.WriteLine(" filename_x.txt - the abscissa file.");
Console.WriteLine(" filename_r.txt - the region file.");
//
// Get ORDER.
//
try
{
order = Convert.ToInt32(args[0]);
}
catch
{
Console.WriteLine("");
Console.WriteLine(" Enter the value of ORDER.");
order = Convert.ToInt32(Console.ReadLine());
}
if (!Order.order_check(order))
{
Console.WriteLine("");
Console.WriteLine("PATTERSON_RULE:");
Console.WriteLine(" ORDER is illegal.");
Console.WriteLine(" Abnormal end of execution.");
return;
}
//
// Get A.
//
try
{
a = Convert.ToDouble(args[1]);
}
catch
{
Console.WriteLine("");
Console.WriteLine(" Enter the left endpoint A:");
a = Convert.ToDouble(Console.ReadLine());
}
//
// Get B.
//
try
{
b = Convert.ToDouble(args[2]);
}
catch
{
Console.WriteLine("");
Console.WriteLine(" Enter the right endpoint B:");
b = Convert.ToDouble(Console.ReadLine());
}
//
// Get FILENAME:
//
try
{
filename = args[3];
}
catch
{
Console.WriteLine("");
Console.WriteLine(" Enter FILENAME, the \"root name\" of the quadrature files).");
filename = Console.ReadLine();
}
//
// Input summary.
//
Console.WriteLine("");
Console.WriteLine(" ORDER = " + order + "");
Console.WriteLine(" A = " + a + "");
Console.WriteLine(" B = " + b + "");
Console.WriteLine(" FILENAME = \"" + filename + "\".");
//
// Construct the rule.
//
double[] r = new double[2];
double[] w = new double[order];
double[] x = new double[order];
r[0] = a;
r[1] = b;
PattersonQuadrature.patterson_set(order, ref x, ref w);
//
// Rescale the rule.
//
ClenshawCurtis.rescale(a, b, order, ref x, ref w);
//
// Output the rule.
//
QuadratureRule.rule_write(order, filename, x, w, r);
Console.WriteLine("");
Console.WriteLine("PATTERSON_RULE:");
Console.WriteLine(" Normal end of execution.");
Console.WriteLine("");
}
