# sgesc2 (l) - Linux Manuals

## NAME

SGESC2 - 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 SGETC2

## SYNOPSIS

SUBROUTINE SGESC2(
N, A, LDA, RHS, IPIV, JPIV, SCALE )

INTEGER LDA, N

REAL SCALE

INTEGER IPIV( * ), JPIV( * )

REAL A( LDA, * ), RHS( * )

## PURPOSE

SGESC2 solves a system of linear equations

## ARGUMENTS

N (input) INTEGER
The order of the matrix A.
A (input) REAL array, dimension (LDA,N)
On entry, the LU part of the factorization of the n-by-n matrix A computed by SGETC2: A = P * L * U * Q
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1, N).
RHS (input/output) REAL 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) REAL
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.