public static void triang_test( )
//****************************************************************************80
//
// Purpose:
//
// TRIANG_TEST tests TRIANG.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 05 January 2007
//
// Author:
//
// John Burkardt
//
{
const int N = 10;
int[] a =
{
1, 0, 1, 0, 1, 0, 1, 0, 0, 1,
0, 1, 0, 0, 1, 0, 0, 0, 0, 0,
0, 0, 1, 0, 1, 0, 1, 0, 0, 1,
0, 1, 1, 1, 1, 1, 1, 1, 0, 1,
0, 0, 0, 0, 1, 0, 0, 0, 0, 0,
0, 1, 0, 0, 1, 1, 1, 0, 0, 0,
0, 0, 0, 0, 1, 0, 1, 0, 0, 0,
0, 1, 0, 0, 1, 1, 1, 1, 0, 1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 1, 0, 1, 0, 0, 1
};
int[] p = new int[N];
Console.WriteLine("");
Console.WriteLine("TRIANG_TEST");
Console.WriteLine(" TRIANG relabels elements for a partial ordering,");
typeMethods.i4mat_print(N, N, a, " The input matrix:");
Triang.triang(N, a, ref p);
Permutation.perm0_print(N, p, " The new ordering:");
typeMethods.i4mat_2perm0(N, N, a, p, p);
typeMethods.i4mat_print(N, N, a, " The reordered matrix:");
}
public static void moebius_matrix(int n, int[] a, ref int[] mu)
//****************************************************************************80
//
// Purpose:
//
// MOEBIUS_MATRIX finds the Moebius matrix from a covering relation.
//
// Discussion:
//
// This routine can be called with A and MU being the same matrix.
// The routine will correctly compute the Moebius matrix, which
// will, in this case, overwrite the input matrix.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 29 May 2003
//
// Author:
//
// Original FORTRAN77 version by Albert Nijenhuis, Herbert Wilf.
// C++ version by John Burkardt.
//
// Reference:
//
// Albert Nijenhuis, Herbert Wilf,
// Combinatorial Algorithms for Computers and Calculators,
// Second Edition,
// Academic Press, 1978,
// ISBN: 0-12-519260-6,
// LC: QA164.N54.
//
// Parameters:
//
// Input, int N, number of elements in the partially ordered set.
//
// Input, int A[N*N]. A(I,J) = 1 if I is covered by J,
// 0 otherwise.
//
// Output, int MU[N*N], the Moebius matrix as computed by the routine.
//
{
int i;
int j;
int[] p1 = new int[n];
//
// Compute a reordering of the elements of the partially ordered matrix.
//
Triang.triang(n, a, ref p1);
//
// Copy the matrix.
//
for (i = 0; i < n; i++)
{
for (j = 0; j < n; j++)
{
mu[i + j * n] = a[i + j * n];
}
}
//
// Apply the reordering to MU.
//
typeMethods.i4mat_2perm0(n, n, mu, p1, p1);
//
// Negate the (strict) upper triangular elements of MU.
//
for (i = 0; i < n - 1; i++)
{
for (j = i + 1; j < n; j++)
{
mu[i + j * n] = -mu[i + j * n];
}
}
//
// Compute the inverse of MU.
//
typeMethods.i4mat_u1_inverse(n, mu, ref mu);
//
// All nonzero elements are reset to 1.
//
for (i = 0; i < n; i++)
{
for (j = i; j < n; j++)
{
if (mu[i + j * n] != 0)
{
mu[i + j * n] = 1;
}
}
}
//
// Invert the matrix again.
//
typeMethods.i4mat_u1_inverse(n, mu, ref mu);
//
// Compute the inverse permutation.
//
int[] p2 = Permutation.perm0_inverse(n, p1);
//
// Unpermute the rows and columns of MU.
//
typeMethods.i4mat_2perm0(n, n, mu, p2, p2);
}
