Provided by: liblapack-doc_3.3.1-1_all #### NAME

```       LAPACK-3  -  solves  a  system  of linear equations A*X = B with a real symmetric matrix A
using the factorization A = U*D*U**T or A = L*D*L**T computed by ZSYTRF and  converted  by
ZSYCONV

```

#### SYNOPSIS

```       SUBROUTINE ZSYTRS2( UPLO, N, NRHS, A, LDA, IPIV, B, LDB, WORK, INFO )

CHARACTER       UPLO

INTEGER         INFO, LDA, LDB, N, NRHS

INTEGER         IPIV( * )

DOUBLE          COMPLEX A( LDA, * ), B( LDB, * ), WORK( * )

```

#### PURPOSE

```       ZSYTRS2  solves  a system of linear equations A*X = B with a real symmetric matrix A using
the factorization A = U*D*U**T or A  =  L*D*L**T  computed  by  ZSYTRF  and  converted  by
ZSYCONV.

```

#### ARGUMENTS

```        UPLO    (input) CHARACTER*1
Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix.
= 'U':  Upper triangular, 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 COMPLEX array, dimension (LDA,N)
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by ZSYTRF.

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 ZSYTRF.

B       (input/output) DOUBLE COMPLEX 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).

WORK    (workspace) REAL array, dimension (N)

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

LAPACK PROTOTYPE routine (version 3.3.1)   April 2011                           ZSYTRS2(3lapack)
```