QR_MUMPS
Functions/Subroutines
qrm_rowperm.F90 File Reference

this file contains the routine which computes a row permutation that puts the input matrix into a staircase format. More...

Go to the source code of this file.

Functions/Subroutines

subroutine _qrm_rowperm (graph, cperm, rperm, nvar, stair)
 This routine computes a row permutation that puts the input matrix into a staircase format. More...
 

Detailed Description

this file contains the routine which computes a row permutation that puts the input matrix into a staircase format.

Date
2016-01-29 22:22:30 +0100 (Fri, 29 Jan 2016)
Author
abuttari
Version
1.1
Revision
2075

Definition in file qrm_rowperm.F90.

Function/Subroutine Documentation

subroutine _qrm_rowperm ( type(_qrm_spmat_type graph,
integer, dimension(:)  cperm,
integer, dimension(:)  rperm,
integer, dimension(:)  nvar,
integer, dimension(:)  stair 
)

This routine computes a row permutation that puts the input matrix into a staircase format.

This subroutine computes a row permutation rperm such that A(rperm, cperm) is as much as possible upper triangular. The idea is to have someting like:

   |x       |
   |x       |     in this case stair would be:
   | x      |     stair=(/ 2, 5, 7, 7, 9 /)
   | x      |
   | x      |
   |  xx    |
   |  xx    |
   |    x   |
   |    x   |
Parameters
[in]grapha qrm_spmat_type containing the matrix
[in]cperma column permutation
[out]rpermthe computed row permutation
[in]nvarnvar(i) is the number of variables in the node whose principal variable is i
[out]stairstair(i) is the number of rows in step i of the stair structure computed on the input graph

Definition at line 69 of file qrm_rowperm.F90.

Referenced by _qrm_analyse().