/* ========================================================================= */
  /* === AMD demo main program =============================================== */
  /* ========================================================================= */
  
  /* ------------------------------------------------------------------------- */
  /* AMD Copyright (c) by Timothy A. Davis,				     */
  /* Patrick R. Amestoy, and Iain S. Duff.  See ../README.txt for License.     */
  /* email: davis at cise.ufl.edu    CISE Department, Univ. of Florida.        */
  /* web: http://www.cise.ufl.edu/research/sparse/amd                          */
  /* ------------------------------------------------------------------------- */
  
  /* A simple C main program that illustrates the use of the ANSI C interface
   * to AMD.
   */
  
  #include "amd.h"
  #include <stdio.h>
  #include <stdlib.h>
  
  int main (void)
  {
      /* The symmetric can_24 Harwell/Boeing matrix, including upper and lower
       * triangular parts, and the diagonal entries.  Note that this matrix is
       * 0-based, with row and column indices in the range 0 to n-1. */
      int n = 24, nz,
      Ap [ ] = { 0, 9, 15, 21, 27, 33, 39, 48, 57, 61, 70, 76, 82, 88, 94, 100,
  	106, 110, 119, 128, 137, 143, 152, 156, 160 },
      Ai [ ] = {
  	/* column  0: */    0, 5, 6, 12, 13, 17, 18, 19, 21,
  	/* column  1: */    1, 8, 9, 13, 14, 17,
  	/* column  2: */    2, 6, 11, 20, 21, 22,
  	/* column  3: */    3, 7, 10, 15, 18, 19,
  	/* column  4: */    4, 7, 9, 14, 15, 16,
  	/* column  5: */    0, 5, 6, 12, 13, 17,
  	/* column  6: */    0, 2, 5, 6, 11, 12, 19, 21, 23,
  	/* column  7: */    3, 4, 7, 9, 14, 15, 16, 17, 18,
  	/* column  8: */    1, 8, 9, 14,
  	/* column  9: */    1, 4, 7, 8, 9, 13, 14, 17, 18,
  	/* column 10: */    3, 10, 18, 19, 20, 21,
  	/* column 11: */    2, 6, 11, 12, 21, 23,
  	/* column 12: */    0, 5, 6, 11, 12, 23,
  	/* column 13: */    0, 1, 5, 9, 13, 17,
  	/* column 14: */    1, 4, 7, 8, 9, 14,
  	/* column 15: */    3, 4, 7, 15, 16, 18,
  	/* column 16: */    4, 7, 15, 16,
  	/* column 17: */    0, 1, 5, 7, 9, 13, 17, 18, 19,
  	/* column 18: */    0, 3, 7, 9, 10, 15, 17, 18, 19,
  	/* column 19: */    0, 3, 6, 10, 17, 18, 19, 20, 21,
  	/* column 20: */    2, 10, 19, 20, 21, 22,
  	/* column 21: */    0, 2, 6, 10, 11, 19, 20, 21, 22,
  	/* column 22: */    2, 20, 21, 22,
  	/* column 23: */    6, 11, 12, 23 } ;
  
      int P [24], Pinv [24], i, j, k, jnew, p, inew, result ;
      double Control [AMD_CONTROL], Info [AMD_INFO] ;
      char A [24][24] ;
  
      /* here is an example of how to use AMD_VERSION.  This code will work in
       * any version of AMD. */
  #if defined(AMD_VERSION) && (AMD_VERSION >= AMD_VERSION_CODE(1,2))
      printf ("AMD version %d.%d, date: %s
  ", AMD_MAIN_VERSION, AMD_SUB_VERSION,
  	    AMD_DATE) ;
  #else
      printf ("AMD version: 1.1 or earlier
  ") ;
  #endif
  
      printf ("AMD demo, with the 24-by-24 Harwell/Boeing matrix, can_24:
  ") ;
  
      /* get the default parameters, and print them */
      amd_defaults (Control) ;
      amd_control  (Control) ;
  
      /* print the input matrix */
      nz = Ap [n] ;
      printf ("
  Input matrix:  %d-by-%d, with %d entries.
  "
  	   "   Note that for a symmetric matrix such as this one, only the
  "
  	   "   strictly lower or upper triangular parts would need to be
  "
  	   "   passed to AMD, since AMD computes the ordering of A+A'.  The
  "
  	   "   diagonal entries are also not needed, since AMD ignores them.
  "
  	   , n, n, nz) ;
      for (j = 0 ; j < n ; j++)
      {
  	printf ("
  Column: %d, number of entries: %d, with row indices in"
  		" Ai [%d ... %d]:
      row indices:",
  		j, Ap [j+1] - Ap [j], Ap [j], Ap [j+1]-1) ;
  	for (p = Ap [j] ; p < Ap [j+1] ; p++)
  	{
  	    i = Ai [p] ;
  	    printf (" %d", i) ;
  	}
  	printf ("
  ") ;
      }
  
      /* print a character plot of the input matrix.  This is only reasonable
       * because the matrix is small. */
      printf ("
  Plot of input matrix pattern:
  ") ;
      for (j = 0 ; j < n ; j++)
      {
  	for (i = 0 ; i < n ; i++) A [i][j] = '.' ;
  	for (p = Ap [j] ; p < Ap [j+1] ; p++)
  	{
  	    i = Ai [p] ;
  	    A [i][j] = 'X' ;
  	}
      }
      printf ("    ") ;
      for (j = 0 ; j < n ; j++) printf (" %1d", j % 10) ;
      printf ("
  ") ;
      for (i = 0 ; i < n ; i++)
      {
  	printf ("%2d: ", i) ;
  	for (j = 0 ; j < n ; j++)
  	{
  	    printf (" %c", A [i][j]) ;
  	}
  	printf ("
  ") ;
      }
  
      /* order the matrix */
      result = amd_order (n, Ap, Ai, P, Control, Info) ;
      printf ("return value from amd_order: %d (should be %d)
  ",
  	result, AMD_OK) ;
  
      /* print the statistics */
      amd_info (Info) ;
  
      if (result != AMD_OK)
      {
  	printf ("AMD failed
  ") ;
  	exit (1) ;
      }
  
      /* print the permutation vector, P, and compute the inverse permutation */
      printf ("Permutation vector:
  ") ;
      for (k = 0 ; k < n ; k++)
      {
  	/* row/column j is the kth row/column in the permuted matrix */
  	j = P [k] ;
  	Pinv [j] = k ;
  	printf (" %2d", j) ;
      }
      printf ("
  
  ") ;
  
      printf ("Inverse permutation vector:
  ") ;
      for (j = 0 ; j < n ; j++)
      {
  	k = Pinv [j] ;
  	printf (" %2d", k) ;
      }
      printf ("
  
  ") ;
  
      /* print a character plot of the permuted matrix. */
      printf ("
  Plot of permuted matrix pattern:
  ") ;
      for (jnew = 0 ; jnew < n ; jnew++)
      {
  	j = P [jnew] ;
  	for (inew = 0 ; inew < n ; inew++) A [inew][jnew] = '.' ;
  	for (p = Ap [j] ; p < Ap [j+1] ; p++)
  	{
  	    inew = Pinv [Ai [p]] ;
  	    A [inew][jnew] = 'X' ;
  	}
      }
      printf ("    ") ;
      for (j = 0 ; j < n ; j++) printf (" %1d", j % 10) ;
      printf ("
  ") ;
      for (i = 0 ; i < n ; i++)
      {
  	printf ("%2d: ", i) ;
  	for (j = 0 ; j < n ; j++)
  	{
  	    printf (" %c", A [i][j]) ;
  	}
  	printf ("
  ") ;
      }
  
      return (0) ;
  }