sgesc23lapack
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
Usage
- 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.