sp_preorder(3P) Sun Performance Library sp_preorder(3P)NAMEsp_preorder - permutes the columns of the original sparse matrix.
SYNOPSIS
#include <sunperf.h>
void sp_preorder(superlu_options_t *options, SuperMatrix *A, int
*perm_c, int *etree, SuperMatrix *AC)
void sp_preorder_64(superlu_options_t_64 *options, SuperMatrix_64 *A,
long *perm_c, long *etree, SuperMatrix_64 *AC)
PURPOSEsp_preorder permutes the columns of the original sparse matrix. It
performs the following steps:
1. Apply column permutation perm_c[] to A's column pointers to form AC
2. If options->Fact = DOFACT, then
Compute column elimination tree etree[] of AC'AC
Post order etree[] to get a postordered elimination tree
etree[], and a postorder permutation post[]
Apply post[] permutation to columns of AC
Overwrite perm_c[] with the product perm_c * post.
ARGUMENTS
superlu_options_t *options (input)
Specifies whether or not the elimination tree will be re-used.
If options->Fact == DOFACT, this means first time factor A,
etree is computed, postered, and output. Otherwise, re-factor
A; etree is input; unchanged on exit.
SuperMatrix *A (input)
Matrix A in A*X=B, of dimension (A->nrow, A->ncol). The number
of linear equations is A->nrow. Currently, the type of A can be:
Stype = SLU_NC; Dtype = SLU_S; Mtype = SLU_GE.
In the future, more general A may be handled.
int *perm_c (input/output)
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.
If options->Fact == DOFACT, perm_c is both input and output. On
output, it is changed according to a postorder of etree. Other‐
wise, perm_c is input.
int *etree (input)
Elimination tree of Pc'*A'*A*Pc, dimension A->ncol.
If options->Fact == DOFACT, etree is an output argument, other‐
wise it is an input argument. Note: etree is a vector of parent
pointers for a forest whose vertices are the integers 0 to
A->ncol-1; etree[root]==A->ncol.
SuperMatrix *AC (output)
The resulting matrix after applied the column permutation
perm_c[] to matrix A. The type of AC can be:
Stype = SLU_NCP; Dtype = A->Dtype; Mtype = SLU_GE.
COPYRIGHT
Copyright (c) 2003, The Regents of the University of California,
through Lawrence Berkeley National Laboratory (subject to receipt of
any required approvals from U.S. Dept. of Energy)
SEE ALSO
SuperMatrix
set_default_options
http://crd.lbl.gov/~xiaoye/SuperLU/
James W. Demmel, Stanley C. Eisenstat, John R. Gilbert, Xiaoye S. Li
and Joseph W. H. Liu, "A supernodal approach to sparse partial pivot‐
ing", SIAM J. Matrix Analysis and Applications, Vol. 20, Num. 3, 1999,
pp. 720-755.
6 Mar 2009 sp_preorder(3P)
