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

```       LAPACK-3  -  computes  the  Cholesky  factorization  of a real symmetric positive definite
matrix A

```

#### SYNOPSIS

```       SUBROUTINE DPOTRF( UPLO, N, A, LDA, INFO )

CHARACTER      UPLO

INTEGER        INFO, LDA, N

DOUBLE         PRECISION A( LDA, * )

```

#### PURPOSE

```       DPOTRF computes the Cholesky factorization of a real symmetric positive definite matrix A.
The factorization has the form
A = U**T * U,  if UPLO = 'U', or
A = L  * L**T,  if UPLO = 'L',
where U is an upper triangular matrix and L is lower triangular.
This is the block version of the algorithm, calling Level 3 BLAS.

```

#### 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.

A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the symmetric matrix A.  If UPLO = 'U', the leading
N-by-N upper triangular part of A contains the upper
triangular part of the matrix A, and the strictly lower
triangular part of A is not referenced.  If UPLO = 'L', the
leading N-by-N lower triangular part of A contains the lower
triangular part of the matrix A, and the strictly upper
triangular part of A is not referenced.
On exit, if INFO = 0, the factor U or L from the Cholesky
factorization A = U**T*U or A = L*L**T.

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

INFO    (output) INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, the leading minor of order i is not
positive definite, and the factorization could not be
completed.

LAPACK routine (version 3.3.1)             April 2011                            DPOTRF(3lapack)
```