SYNOPSIS

SUBROUTINE DGESC2(

N, A, LDA, RHS, IPIV, JPIV, SCALE )

    

INTEGER LDA, N

    

DOUBLE PRECISION SCALE

    

INTEGER IPIV( * ), JPIV( * )

    

DOUBLE PRECISION A( LDA, * ), RHS( * )

PURPOSE

DGESC2 solves a system of linear equations

ARGUMENTS

N (input) INTEGER

The order of the matrix A.

A (input) DOUBLE PRECISION array, dimension (LDA,N)

On entry, the LU part of the factorization of the n-by-n matrix A computed by DGETC2: A = P * L * U * Q

LDA (input) INTEGER

The leading dimension of the array A. LDA >= max(1, N).

RHS (input/output) DOUBLE PRECISION array, dimension (N).

On entry, the right hand side vector b. On exit, the solution vector X.

IPIV (input) INTEGER array, dimension (N).

The pivot indices; for 1 <= i <= N, row i of the matrix has been interchanged with row IPIV(i).

JPIV (input) INTEGER array, dimension (N).

The pivot indices; for 1 <= j <= N, column j of the matrix has been interchanged with column JPIV(j).

SCALE (output) DOUBLE PRECISION

On exit, SCALE contains the scale factor. SCALE is chosen 0 <= SCALE <= 1 to prevent owerflow in the solution.

FURTHER DETAILS

Based on contributions by

   Bo Kagstrom and Peter Poromaa, Department of Computing Science,
   Umea University, S-901 87 Umea, Sweden.