DGETRS(l) ) DGETRS(l)NAME
DGETRS - solve a system of linear equations A * X = B or A' * 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 A' * 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:
= 'N': A * X = B (No transpose)
= 'T': A'* X = B (Transpose)
= 'C': A'* 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 com‐
puted 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
LAPACK version 3.0 15 June 2000 DGETRS(l)
