diff -r d59bea55db9b -r c445c931472f src/amd/amd_valid.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/amd/amd_valid.c	Mon Dec 06 13:09:21 2010 +0100
@@ -0,0 +1,93 @@
+/* ========================================================================= */
+/* === AMD_valid =========================================================== */
+/* ========================================================================= */
+
+/* ------------------------------------------------------------------------- */
+/* AMD, Copyright (c) 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                          */
+/* ------------------------------------------------------------------------- */
+
+/* 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"
+
+GLOBAL 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, 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) ;
+}