DPOTF2(3)      LAPACK routine of NEC Numeric Library Collection      DPOTF2(3)



NAME
       DPOTF2

SYNOPSIS
       SUBROUTINE DPOTF2 (UPLO, N, A, LDA, INFO)



PURPOSE
            DPOTF2 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 unblocked version of the algorithm, calling Level 2 BLAS.




ARGUMENTS
           UPLO      (input)
                     UPLO is CHARACTER*1
                     Specifies whether the upper or lower triangular part of the
                     symmetric matrix A is stored.
                     = 'U':  Upper triangular
                     = 'L':  Lower triangular

           N         (input)
                     N is INTEGER
                     The order of the matrix A.  N >= 0.

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

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



LAPACK routine                  31 October 2017                      DPOTF2(3)