[ новости /+++ | форум | теги | ]

NAME
     spotrf - compute the Cholesky factorization of a  real  sym-
     metric positive definite matrix A

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

     CHARACTER UPLO

     INTEGER INFO, LDA, N

     REAL A( LDA, * )



     #include <sunperf.h>

     void spotrf(char uplo, int n, float *sa, int lda, int *info)
               ;

PURPOSE
     SPOTRF computes the Cholesky factorization of  a  real  sym-
     metric 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  tri-
     angular.

     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) REAL array, dimension (LDA,N)
               On entry, the symmetric matrix A.  If UPLO =  'U',
               the leading N-by-N upper triangular part of A con-
               tains 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 tri-
               angular 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 ille-
               gal value
               > 0:  if INFO = i, the leading minor of order i is
               not positive definite, and the factorization could
               not be completed.

Партнёры:

Хостинг: