DSYTRS(1) LAPACK routine (version 3.2) DSYTRS(1)NAME
DSYTRS - solves a system of linear equations A*X = B with a real sym‐
metric matrix A using the factorization A = U*D*U**T or A = L*D*L**T
computed by DSYTRF
SYNOPSIS
SUBROUTINE DSYTRS( UPLO, N, NRHS, A, LDA, IPIV, B, LDB, INFO )
CHARACTER UPLO
INTEGER INFO, LDA, LDB, N, NRHS
INTEGER IPIV( * )
DOUBLE PRECISION A( LDA, * ), B( LDB, * )
PURPOSE
DSYTRS solves a system of linear equations A*X = B with a real symmet‐
ric matrix A using the factorization A = U*D*U**T or A = L*D*L**T com‐
puted by DSYTRF.
ARGUMENTS
UPLO (input) CHARACTER*1
Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix. = 'U': Upper triangu‐
lar, form is A = U*D*U**T;
= 'L': Lower triangular, form is A = L*D*L**T.
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 block diagonal matrix D and the multipliers used to obtain
the factor U or L as computed by DSYTRF.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
IPIV (input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D as
determined by DSYTRF.
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 routine (version 3.2) November 2008 DSYTRS(1)
