private static void test18()
//****************************************************************************80
//
// Purpose:
//
// TEST18 tests ROOTS_TO_DIF and DIF_TO_R8POLY.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 18 January 2007
//
// Author:
//
// John Burkardt
//
{
const int MAXROOTS = 4;
double[] c = new double[MAXROOTS + 1];
double[] diftab = new double[MAXROOTS + 1];
int ntab = 0;
double[] roots = new double[MAXROOTS];
double[] xtab = new double[MAXROOTS + 1];
Console.WriteLine("");
Console.WriteLine("TEST18");
Console.WriteLine(" ROOTS_TO_DIF computes a divided difference");
Console.WriteLine(" polynomial with the given roots;");
Console.WriteLine(" DIF_TO_R8POLY converts it to a standard form polynomial.");
Console.WriteLine("");
int nroots = 1;
roots[0] = 3.0;
typeMethods.r8vec_print(nroots, roots, " The roots:");
Roots.roots_to_dif(nroots, roots, ref ntab, ref xtab, ref diftab);
Dif.dif_to_r8poly(ntab, xtab, diftab, ref c);
typeMethods.r8poly_print(ntab, c, " The polynomial:");
nroots = 2;
roots[0] = 3.0;
roots[1] = 1.0;
typeMethods.r8vec_print(nroots, roots, " The roots:");
Roots.roots_to_dif(nroots, roots, ref ntab, ref xtab, ref diftab);
Dif.dif_to_r8poly(ntab, xtab, diftab, ref c);
typeMethods.r8poly_print(ntab, c, " The polynomial:");
nroots = 3;
roots[0] = 3.0;
roots[1] = 1.0;
roots[2] = 2.0;
typeMethods.r8vec_print(nroots, roots, " The roots:");
Roots.roots_to_dif(nroots, roots, ref ntab, ref xtab, ref diftab);
Dif.dif_to_r8poly(ntab, xtab, diftab, ref c);
typeMethods.r8poly_print(ntab, c, " The polynomial:");
nroots = 4;
roots[0] = 3.0;
roots[1] = 1.0;
roots[2] = 2.0;
roots[3] = 4.0;
typeMethods.r8vec_print(nroots, roots, " The roots:");
Roots.roots_to_dif(nroots, roots, ref ntab, ref xtab, ref diftab);
Dif.dif_to_r8poly(ntab, xtab, diftab, ref c);
typeMethods.r8poly_print(ntab, c, " The polynomial:");
}