SuperLU  5.0
Functions
get_perm_c.c File Reference

Matrix permutation operations. More...

#include "slu_ddefs.h"
#include "colamd.h"
Include dependency graph for get_perm_c.c:

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)
 

Detailed Description

– SuperLU routine (version 3.1) –
Univ. of California Berkeley, Xerox Palo Alto Research Center,
and Lawrence Berkeley National Lab.
August 1, 2008

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

Here is the call graph for this function:

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

Here is the call graph for this function:

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.

Here is the call graph for this function:

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?