dgetrs (l) - Linux Manuals

dgetrs: solves a system of linear equations A * X = B or Aaq * X = B with a general N-by-N matrix A using the LU factorization computed by DGETRF

NAME

DGETRS - solves a system of linear equations A * X = B or Aaq * X = B with a general N-by-N matrix A using the LU factorization computed by DGETRF

SYNOPSIS

SUBROUTINE DGETRS(

TRANS, N, NRHS, A, LDA, IPIV, B, LDB, INFO )

    

CHARACTER TRANS

    

INTEGER INFO, LDA, LDB, N, NRHS

    

INTEGER IPIV( * )

    

DOUBLE PRECISION A( LDA, * ), B( LDB, * )

PURPOSE

DGETRS solves a system of linear equations
A * X = B  or  Aaq * X = B with a general N-by-N matrix A using the LU factorization computed by DGETRF.

ARGUMENTS

TRANS (input) CHARACTER*1

Specifies the form of the system of equations:
= aqNaq: A * X = B (No transpose)
= aqTaq: Aaq* X = B (Transpose)
= aqCaq: Aaq* X = B (Conjugate transpose = Transpose)

N (input) INTEGER

The order of the matrix A. N >= 0.

NRHS (input) INTEGER

The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.

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

The factors L and U from the factorization A = P*L*U as computed by DGETRF.

LDA (input) INTEGER

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

IPIV (input) INTEGER array, dimension (N)

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

B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)

On entry, the right hand side matrix B. On exit, the solution matrix X.

LDB (input) INTEGER

The leading dimension of the array B. LDB >= max(1,N).

INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value