lsd_mkb/lsd_mkb_superlu/superlu_seq/get_perm_c.c File Reference

#include "slu_ddefs.h"
#include "colamd.h"

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Functions
int	genmmd_ (int *, int *, int *, int *, int *, int *, int *, int *, int *, int *, int *, int *)
void	get_colamd (const int m, const int n, const int nnz, int *colptr, int *rowind, int *perm_c)
void	getata (const int m, const int n, const int nz, int *colptr, int *rowind, int *atanz, int **ata_colptr, int **ata_rowind)
void	at_plus_a (const int n, const int nz, int *colptr, int *rowind, int *bnz, int **b_colptr, int **b_rowind)
void	get_perm_c (int ispec, SuperMatrix *A, int *perm_c)

---

Function Documentation

void at_plus_a	(	const int	n,
		const int	nz,
		int *	colptr,
		int *	rowind,
		int *	bnz,
		int **	b_colptr,
		int **	b_rowind
	)

 Purpose
 =======

 Form the structure of A'+A. A is an n-by-n matrix in column oriented
 format represented by (colptr, rowind). The output A'+A is in column
 oriented format (symmetrically, also row oriented), represented by
 (b_colptr, b_rowind).
 

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int genmmd_	(	int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *
	)

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void get_colamd	(	const int	m,
		const int	n,
		const int	nnz,
		int *	colptr,
		int *	rowind,
		int *	perm_c
	)

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void get_perm_c	(	int	ispec,
		SuperMatrix *	A,
		int *	perm_c
	)

 Purpose
 =======

 GET_PERM_C obtains a permutation matrix Pc, by applying the multiple
 minimum degree ordering code by Joseph Liu to matrix A'*A or A+A'.
 or using approximate minimum degree column ordering by Davis et. al.
 The LU factorization of A*Pc tends to have less fill than the LU 
 factorization of A.

 Arguments
 =========

 ispec   (input) int
         Specifies the type of column ordering to reduce fill:
         = 1: minimum degree on the structure of A^T * A
         = 2: minimum degree on the structure of A^T + A
         = 3: approximate minimum degree for unsymmetric matrices
         If ispec == 0, the natural ordering (i.e., Pc = I) is returned.

 A       (input) SuperMatrix*
         Matrix A in A*X=B, of dimension (A->nrow, A->ncol). The number
         of the linear equations is A->nrow. Currently, the type of A 
         can be: Stype = NC; Dtype = _D; Mtype = GE. In the future,
         more general A can be handled.

 perm_c  (output) int*
	   Column permutation vector of size A->ncol, which defines the 
         permutation matrix Pc; perm_c[i] = j means column i of A is 
         in position j in A*Pc.
 

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void getata	(	const int	m,
		const int	n,
		const int	nz,
		int *	colptr,
		int *	rowind,
		int *	atanz,
		int **	ata_colptr,
		int **	ata_rowind
	)

 Purpose
 =======

 Form the structure of A'*A. A is an m-by-n matrix in column oriented
 format represented by (colptr, rowind). The output A'*A is in column
 oriented format (symmetrically, also row oriented), represented by
 (ata_colptr, ata_rowind).

 This routine is modified from GETATA routine by Tim Davis.
 The complexity of this algorithm is: SUM_{i=1,m} r(i)^2,
 i.e., the sum of the square of the row counts.

 Questions
 =========
     o  Do I need to withhold the *dense* rows?
     o  How do I know the number of nonzeros in A'*A?
 

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