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

```       LAPACK-3  - solves a system of linear equations A*X = B with a symmetric positive definite
matrix A in packed storage using the Cholesky factorization A  =  U**T*U  or  A  =  L*L**T
computed by SPPTRF

```

#### SYNOPSIS

```       SUBROUTINE SPPTRS( UPLO, N, NRHS, AP, B, LDB, INFO )

CHARACTER      UPLO

INTEGER        INFO, LDB, N, NRHS

REAL           AP( * ), B( LDB, * )

```

#### PURPOSE

```       SPPTRS  solves  a  system  of  linear equations A*X = B with a symmetric positive definite
matrix A in packed storage using the Cholesky factorization A  =  U**T*U  or  A  =  L*L**T
computed by SPPTRF.

```

#### ARGUMENTS

```        UPLO    (input) CHARACTER*1
= 'U':  Upper triangle of A is stored;
= 'L':  Lower triangle of A is stored.

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.

AP      (input) REAL array, dimension (N*(N+1)/2)
The triangular factor U or L from the Cholesky factorization
A = U**T*U or A = L*L**T, packed columnwise in a linear
array.  The j-th column of U or L is stored in the array AP
as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.

B       (input/output) REAL 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 3.3.1)             April 2011                            SPPTRS(3lapack)
```