edu.ufl.cise.amd.tdouble.Damd_valid Maven / Gradle / Ivy

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/**
 * AMD, Copyright (C) 2009-2011 by Timothy A. Davis, Patrick R. Amestoy,
 * and Iain S. Duff.  All Rights Reserved.
 * Copyright (C) 2011 Richard Lincoln
 *
 * AMD is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * AMD is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with AMD; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
 */

package edu.ufl.cise.amd.tdouble;

/**
 * Check if a column-form matrix is valid or not.  The matrix A is
 * n_row-by-n_col.  The row indices of entries in column j are in
 * Ai [Ap [j] ... Ap [j+1]-1].  Required conditions are:
 *
 *	n_row >= 0
 *	n_col >= 0
 *	nz = Ap [n_col] >= 0	    number of entries in the matrix
 *	Ap [0] == 0
 *	Ap [j] <= Ap [j+1] for all j in the range 0 to n_col.
 *      Ai [0 ... nz-1] must be in the range 0 to n_row-1.
 *
 * If any of the above conditions hold, AMD_INVALID is returned.  If the
 * following condition holds, AMD_OK_BUT_JUMBLED is returned (a warning,
 * not an error):
 *
 *	row indices in Ai [Ap [j] ... Ap [j+1]-1] are not sorted in ascending
 *	    order, and/or duplicate entries exist.
 *
 * Otherwise, AMD_OK is returned.
 *
 * In v1.2 and earlier, this function returned TRUE if the matrix was valid
 * (now returns AMD_OK), or FALSE otherwise (now returns AMD_INVALID or
 * AMD_OK_BUT_JUMBLED).
 */
public class Damd_valid extends Damd_internal {

	/**
	 *
	 * @param n_row A is n_row-by-n_col
	 * @param n_col
	 * @param Ap column pointers of A, of size n_col+1
	 * @param Ai row indices of A, of size nz = Ap [n_col]
	 * @return
	 */
	public static int amd_valid (int n_row, int n_col, final int[] Ap,
			final int[] Ai)
	{
		int nz, j, p1, p2, ilast, i, p, result = AMD_OK ;

		if (n_row < 0 || n_col < 0 || Ap == null || Ai == null)
		{
		return (AMD_INVALID) ;
		}
		nz = Ap [n_col] ;
		if (Ap [0] != 0 || nz < 0)
		{
		/* column pointers must start at Ap [0] = 0, and Ap [n] must be >= 0 */
		AMD_DEBUG0 ("column 0 pointer bad or nz < 0\n") ;
		return (AMD_INVALID) ;
		}
		for (j = 0 ; j < n_col ; j++)
		{
		p1 = Ap [j] ;
		p2 = Ap [j+1] ;
		AMD_DEBUG2 ("\nColumn: "+ID+" p1: "+ID+" p2: "+ID+"\n", j, p1, p2) ;
		if (p1 > p2)
		{
			/* column pointers must be ascending */
			AMD_DEBUG0 ("column "+ID+" pointer bad\n", j) ;
			return (AMD_INVALID) ;
		}
		ilast = EMPTY ;
		for (p = p1 ; p < p2 ; p++)
		{
			i = Ai [p] ;
			AMD_DEBUG3 ("row: "+ID+"\n", i) ;
			if (i < 0 || i >= n_row)
			{
			/* row index out of range */
			AMD_DEBUG0 ("index out of range, col "+ID+" row "+ID+"\n", j, i) ;
			return (AMD_INVALID) ;
			}
			if (i <= ilast)
			{
			/* row index unsorted, or duplicate entry present */
			AMD_DEBUG1 ("index unsorted/dupl col "+ID+" row "+ID+"\n", j, i) ;
			result = AMD_OK_BUT_JUMBLED ;
			}
			ilast = i ;
		}
		}
		return (result) ;
	}
}