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//------------------------------------------------------------------------------
// AMD/Source/amd_valid: check if a matrix is valid for AMD
//------------------------------------------------------------------------------
// AMD, Copyright (c) 1996-2022, Timothy A. Davis, Patrick R. Amestoy, and
// Iain S. Duff. All Rights Reserved.
// SPDX-License-Identifier: BSD-3-clause
//------------------------------------------------------------------------------
/* 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).
*/
#include "amd_internal.h"
int AMD_valid
(
/* inputs, not modified on output: */
Int n_row, /* A is n_row-by-n_col */
Int n_col,
const Int Ap [ ], /* column pointers of A, of size n_col+1 */
const Int Ai [ ] /* row indices of A, of size nz = Ap [n_col] */
)
{
Int nz, j, p1, p2, ilast, i, p ;
int 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) ;
}
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