dsytf2_rook (3p)

Name

dsytf2_rook - compute the factorization of a real symmetric indefinite matrix using the bounded Bunch-Kaufman ("rook") diagonal pivoting method (unblocked algorithm)

Synopsis

SUBROUTINE DSYTF2_ROOK(UPLO, N, A, LDA, IPIV, INFO)


CHARACTER*1 UPLO

INTEGER INFO, LDA, N

INTEGER IPIV(*)

DOUBLE PRECISION A(LDA,*)


SUBROUTINE DSYTF2_ROOK_64(UPLO, N, A, LDA, IPIV, INFO)


CHARACTER*1 UPLO

INTEGER*8 INFO, LDA, N

INTEGER*8 IPIV(*)

DOUBLE PRECISION A(LDA,*)


F95 INTERFACE
SUBROUTINE SYTF2_ROOK(UPLO, N, A, LDA, IPIV, INFO)


INTEGER :: N, LDA, INFO

CHARACTER(LEN=1) :: UPLO

INTEGER, DIMENSION(:) :: IPIV

REAL(8), DIMENSION(:,:) :: A


SUBROUTINE SYTF2_ROOK_64(UPLO, N, A, LDA, IPIV, INFO)


INTEGER(8) :: N, LDA, INFO

CHARACTER(LEN=1) :: UPLO

INTEGER(8), DIMENSION(:) :: IPIV

REAL(8), DIMENSION(:,:) :: A


C INTERFACE
#include <sunperf.h>

void  dsytf2_rook (char uplo, int n, double *a, int lda, int *ipiv, int
*info);


void dsytf2_rook_64 (char uplo, long  n,  double  *a,  long  lda,  long
*ipiv, long *info);

Description

Oracle Solaris Studio Performance Library                      dsytf2_rook(3P)



NAME
       dsytf2_rook  - compute the factorization of a real symmetric indefinite
       matrix using  the  bounded  Bunch-Kaufman  ("rook")  diagonal  pivoting
       method (unblocked algorithm)


SYNOPSIS
       SUBROUTINE DSYTF2_ROOK(UPLO, N, A, LDA, IPIV, INFO)


       CHARACTER*1 UPLO

       INTEGER INFO, LDA, N

       INTEGER IPIV(*)

       DOUBLE PRECISION A(LDA,*)


       SUBROUTINE DSYTF2_ROOK_64(UPLO, N, A, LDA, IPIV, INFO)


       CHARACTER*1 UPLO

       INTEGER*8 INFO, LDA, N

       INTEGER*8 IPIV(*)

       DOUBLE PRECISION A(LDA,*)


   F95 INTERFACE
       SUBROUTINE SYTF2_ROOK(UPLO, N, A, LDA, IPIV, INFO)


       INTEGER :: N, LDA, INFO

       CHARACTER(LEN=1) :: UPLO

       INTEGER, DIMENSION(:) :: IPIV

       REAL(8), DIMENSION(:,:) :: A


       SUBROUTINE SYTF2_ROOK_64(UPLO, N, A, LDA, IPIV, INFO)


       INTEGER(8) :: N, LDA, INFO

       CHARACTER(LEN=1) :: UPLO

       INTEGER(8), DIMENSION(:) :: IPIV

       REAL(8), DIMENSION(:,:) :: A


   C INTERFACE
       #include <sunperf.h>

       void  dsytf2_rook (char uplo, int n, double *a, int lda, int *ipiv, int
                 *info);


       void dsytf2_rook_64 (char uplo, long  n,  double  *a,  long  lda,  long
                 *ipiv, long *info);


PURPOSE
       dsytf2_rook  computes  the  factorization  of a real symmetric matrix A
       using the bounded Bunch-Kaufman ("rook") diagonal pivoting method:

       A = U*D*U**T  or  A = L*D*L**T

       where U (or L) is a product of permutation and unit upper (lower)  tri-
       angular  matrices,  U**T  is the transpose of U, and D is symmetric and
       block diagonal with 1-by-1 and 2-by-2 diagonal blocks.

       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, the block diagonal matrix D and the multipliers used
                 to obtain the factor U or L (see below for further  details).


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


       IPIV (output)
                 IPIV is INTEGER array, dimension (N)
                 Details of the interchanges and the block structure of D.
                 If UPLO = 'U':
                 If  IPIV(k)  >  0,  then  rows and columns k and IPIV(k) were
                 interchanged and D(k,k) is a 1-by-1 diagonal block.
                 If IPIV(k) < 0 and IPIV(k-1) < 0, then rows and columns k and
                 -IPIV(k)  were  interchanged  and  rows  and  columns k-1 and
                 -IPIV(k-1) were inerchaged, D(k-1:k,k-1:k) is a 2-by-2 diago-
                 nal block.
                 If UPLO = 'L':
                 If  IPIV(k)  >  0,  then  rows and columns k and IPIV(k) were
                 interchanged and D(k,k) is a 1-by-1 diagonal block.
                 If IPIV(k) < 0 and IPIV(k+1) < 0, then rows and columns k and
                 -IPIV(k)  were  interchanged  and  rows  and  columns k+1 and
                 -IPIV(k+1) were inerchaged, D(k:k+1,k:k+1) is a 2-by-2 diago-
                 nal block.


       INFO (output)
                 INFO is INTEGER
                 = 0: successful exit;
                 < 0: if INFO = -k, the k-th argument had an illegal value;
                 >  0:  if INFO = k, D(k,k) is exactly zero. The factorization
                 has been completed,  but  the  block  diagonal  matrix  D  is
                 exactly  singular,  and  division by zero will occur if it is
                 used to solve a system of equations.




                                  7 Nov 2015                   dsytf2_rook(3P)