public static void laguerre_polynomial_test04()
//****************************************************************************80
//
// Purpose:
//
// LAGUERRE_POLYNOMIAL_TEST04 tests L_QUADRATURE_RULE.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 11 March 2012
//
// Author:
//
// John Burkardt
//
{
int e;
double[] f;
int i;
int n;
double q;
double q_exact;
double[] w;
double[] x;
Console.WriteLine("");
Console.WriteLine("LAGUERRE_POLYNOMIAL_TEST04:");
Console.WriteLine(" L_QUADRATURE_RULE computes the quadrature rule");
Console.WriteLine(" associated with L(n,x)");
n = 7;
x = new double[n];
w = new double[n];
QuadratureRule.l_quadrature_rule(n, ref x, ref w);
typeMethods.r8vec2_print(n, x, w, " X W");
Console.WriteLine("");
Console.WriteLine(" Use the quadrature rule to estimate:");
Console.WriteLine("");
Console.WriteLine(" Q = Integral ( 0 <= X < +00 ) X^E exp(-X) dx");
Console.WriteLine("");
Console.WriteLine(" E Q_Estimate Q_Exact");
Console.WriteLine("");
f = new double[n];
for (e = 0; e <= 2 * n - 1; e++)
{
switch (e)
{
case 0:
{
for (i = 0; i < n; i++)
{
f[i] = 1.0;
}
break;
}
default:
{
for (i = 0; i < n; i++)
{
f[i] = Math.Pow(x[i], e);
}
break;
}
}
q = typeMethods.r8vec_dot_product(n, w, f);
q_exact = Laguerre.l_integral(e);
Console.WriteLine(" " + e.ToString().PadLeft(2)
+ " " + q.ToString().PadLeft(14)
+ " " + q_exact.ToString().PadLeft(14) + "");
}
}