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/* ========================================================================= */
/* === AMD_preprocess ====================================================== */
/* ========================================================================= */
/* ------------------------------------------------------------------------- */
/* AMD Version 1.1 (Jan. 21, 2004), Copyright (c) 2004 by Timothy A. Davis, */
/* Patrick R. Amestoy, and Iain S. Duff. See ../README for License. */
/* email: davis@cise.ufl.edu CISE Department, Univ. of Florida. */
/* web: http://www.cise.ufl.edu/research/sparse/amd */
/* ------------------------------------------------------------------------- */
/* Sorts, removes duplicate entries, and transposes from the nonzero pattern of
* a column-form matrix A, to obtain the matrix R.
* See amd.h for a complete description of AMD_preprocess
*/
#include "amd_internal.h"
GLOBAL Int AMD_preprocess /* returns AMD_OK if input is OK, AMD_INVALID
* if the matrix is invalid, or AMD_OUT_OF_MEMORY
* if out of memory for the 2n workspace. */
(
Int n, /* input matrix: A is n-by-n */
const Int Ap [ ], /* size n+1 */
const Int Ai [ ], /* size nz = Ap [n] */
/* output matrix R: */
Int Rp [ ], /* size n+1 */
Int Ri [ ] /* size nz (or less, if duplicates present) */
)
{
/* --------------------------------------------------------------------- */
/* local variables */
/* --------------------------------------------------------------------- */
Int *Flag, *W ;
/* --------------------------------------------------------------------- */
/* check inputs (note: fewer restrictions than AMD_order) */
/* --------------------------------------------------------------------- */
if (!AMD_preprocess_valid (n, Ap, Ai) || !Ri || !Rp)
{
return (AMD_INVALID) ;
}
/* --------------------------------------------------------------------- */
/* allocate workspace */
/* --------------------------------------------------------------------- */
W = (Int *) ALLOCATE (MAX (n,1) * sizeof (Int)) ;
if (!W)
{
return (AMD_OUT_OF_MEMORY) ;
}
Flag = (Int *) ALLOCATE (MAX (n,1) * sizeof (Int)) ;
if (!Flag)
{
FREE (W) ;
return (AMD_OUT_OF_MEMORY) ;
}
/* --------------------------------------------------------------------- */
/* preprocess the matrix: sort, remove duplicates, and transpose */
/* --------------------------------------------------------------------- */
AMD_wpreprocess (n, Ap, Ai, Rp, Ri, W, Flag) ;
/* --------------------------------------------------------------------- */
/* free the workspace */
/* --------------------------------------------------------------------- */
FREE (W) ;
FREE (Flag) ;
return (AMD_OK) ;
}
/* ========================================================================= */
/* === AMD_wpreprocess ===================================================== */
/* ========================================================================= */
/* The AMD_wpreprocess routine is not user-callable. It does not check its
* input for errors or allocate workspace (that is done by the user-callable
* AMD_preprocess routine). It does handle the n=0 case. */
GLOBAL void AMD_wpreprocess
(
Int n, /* input matrix: A is n-by-n */
const Int Ap [ ], /* size n+1 */
const Int Ai [ ], /* size nz = Ap [n] */
/* output matrix R: */
Int Rp [ ], /* size n+1 */
Int Ri [ ], /* size nz (or less, if duplicates present) */
Int W [ ], /* workspace of size n */
Int Flag [ ] /* workspace of size n */
)
{
/* --------------------------------------------------------------------- */
/* local variables */
/* --------------------------------------------------------------------- */
Int i, j, p, p2 ;
/* --------------------------------------------------------------------- */
/* count the entries in each row of A (excluding duplicates) */
/* --------------------------------------------------------------------- */
for (i = 0 ; i < n ; i++)
{
W [i] = 0 ; /* # of nonzeros in row i (excl duplicates) */
Flag [i] = EMPTY ; /* Flag [i] = j if i appears in column j */
}
for (j = 0 ; j < n ; j++)
{
p2 = Ap [j+1] ;
for (p = Ap [j] ; p < p2 ; p++)
{
i = Ai [p] ;
if (Flag [i] != j)
{
/* row index i has not yet appeared in column j */
W [i]++ ; /* one more entry in row i */
Flag [i] = j ; /* flag row index i as appearing in col j*/
}
}
}
/* --------------------------------------------------------------------- */
/* compute the row pointers for R */
/* --------------------------------------------------------------------- */
Rp [0] = 0 ;
for (i = 0 ; i < n ; i++)
{
Rp [i+1] = Rp [i] + W [i] ;
}
for (i = 0 ; i < n ; i++)
{
W [i] = Rp [i] ;
Flag [i] = EMPTY ;
}
/* --------------------------------------------------------------------- */
/* construct the row form matrix R */
/* --------------------------------------------------------------------- */
/* R = row form of pattern of A */
for (j = 0 ; j < n ; j++)
{
p2 = Ap [j+1] ;
for (p = Ap [j] ; p < p2 ; p++)
{
i = Ai [p] ;
if (Flag [i] != j)
{
/* row index i has not yet appeared in column j */
Ri [W [i]++] = j ; /* put col j in row i */
Flag [i] = j ; /* flag row index i as appearing in col j*/
}
}
}
#ifndef NDEBUG
for (j = 0 ; j < n ; j++)
{
ASSERT (W [j] == Rp [j+1]) ;
}
ASSERT (AMD_valid (n, n, Rp, Ri)) ;
#endif
}
/* ========================================================================= */
/* === AMD_preprocess_valid ================================================ */
/* ========================================================================= */
/* Not user-callable. Checks a matrix and returns TRUE if it is valid as input
* to AMD_wpreprocess, FALSE otherwise. */
GLOBAL Int AMD_preprocess_valid
(
Int n,
const Int Ap [ ],
const Int Ai [ ]
)
{
Int i, j, p, nz ;
if (n < 0 || !Ai || !Ap)
{
return (FALSE) ;
}
nz = Ap [n] ;
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 (FALSE) ;
}
for (j = 0 ; j < n ; j++)
{
if (Ap [j] > Ap [j+1])
{
/* column pointers must be ascending */
AMD_DEBUG0 (("column "ID" pointer bad\n", j)) ;
return (FALSE) ;
}
}
for (p = 0 ; p < nz ; p++)
{
i = Ai [p] ;
AMD_DEBUG3 (("row: "ID"\n", i)) ;
if (i < 0 || i >= n)
{
/* row index out of range */
AMD_DEBUG0 (("index out of range, col "ID" row "ID"\n", j, i)) ;
return (FALSE) ;
}
}
return (TRUE) ;
}
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