# dgesc2 (l) - Linux Man Pages

## NAME

DGESC2 - solves a system of linear equations A * X = scale* RHS with a general N-by-N matrix A using the LU factorization with complete pivoting computed by DGETC2

## 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.