sgesc2 (l) - Linux Manuals

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

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.

Pages related to sgesc2

  • sgesc2 (3)
  • sgesdd (l) - computes the singular value decomposition (SVD) of a real M-by-N matrix A, optionally computing the left and right singular vectors
  • sgesv (l) - computes the solution to a real system of linear equations A * X = B,
  • sgesvd (l) - computes the singular value decomposition (SVD) of a real M-by-N matrix A, optionally computing the left and/or right singular vectors
  • sgesvj (l) - computes the singular value decomposition (SVD) of a real M-by-N matrix A, where M >= N
  • sgesvx (l) - uses the LU factorization to compute the solution to a real system of linear equations A * X = B,
  • sgesvxx (l) - SGESVXX use the LU factorization to compute the solution to a real system of linear equations A * X = B, where A is an N-by-N matrix and X and B are N-by-NRHS matrices
  • sgebak (l) - forms the right or left eigenvectors of a real general matrix by backward transformation on the computed eigenvectors of the balanced matrix output by SGEBAL