ssytrs.f −

**Functions/Subroutines**

subroutine **ssytrs** (UPLO, N, NRHS, A, LDA, IPIV, B, LDB, INFO)

SSYTRS

**subroutine ssytrs (characterUPLO, integerN, integerNRHS, real, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, real, dimension( ldb, * )B, integerLDB, integerINFO)
SSYTRS**

**Purpose:**

SSYTRS 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 SSYTRF.

**Parameters:**

*UPLO*

UPLO is 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*

N is INTEGER

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

*NRHS*

NRHS is INTEGER

The number of right hand sides, i.e., the number of columns

of the matrix B. NRHS >= 0.

*A*

A is REAL array, dimension (LDA,N)

The block diagonal matrix D and the multipliers used to

obtain the factor U or L as computed by SSYTRF.

*LDA*

LDA is INTEGER

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

*IPIV*

IPIV is INTEGER array, dimension (N)

Details of the interchanges and the block structure of D

as determined by SSYTRF.

*B*

B is REAL array, dimension (LDB,NRHS)

On entry, the right hand side matrix B.

On exit, the solution matrix X.

*LDB*

LDB is INTEGER

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

*INFO*

INFO is INTEGER

= 0: successful exit

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

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

November 2011

Definition at line 121 of file ssytrs.f.

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