dorgbr (3p)

Name

dorgbr - mined by DGEBRD when reducing a real matrix A to bidiagonal form

Synopsis

SUBROUTINE DORGBR(VECT, M, N, K, A, LDA, TAU, WORK, LWORK, INFO)

CHARACTER*1 VECT
INTEGER M, N, K, LDA, LWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)

SUBROUTINE DORGBR_64(VECT, M, N, K, A, LDA, TAU, WORK, LWORK, INFO)

CHARACTER*1 VECT
INTEGER*8 M, N, K, LDA, LWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)




F95 INTERFACE
SUBROUTINE ORGBR(VECT, M, N, K, A, LDA, TAU, WORK, LWORK,
INFO)

CHARACTER(LEN=1) :: VECT
INTEGER :: M, N, K, LDA, LWORK, INFO
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A

SUBROUTINE ORGBR_64(VECT, M, N, K, A, LDA, TAU, WORK, LWORK,
INFO)

CHARACTER(LEN=1) :: VECT
INTEGER(8) :: M, N, K, LDA, LWORK, INFO
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A




C INTERFACE
#include <sunperf.h>

void dorgbr(char vect, int m, int n, int k, double *a, int lda,  double
*tau, int *info);

void  dorgbr_64(char vect, long m, long n, long k, double *a, long lda,
double *tau, long *info);

Description

Oracle Solaris Studio Performance Library                           dorgbr(3P)



NAME
       dorgbr  - generate one of the real orthogonal matrices Q or P**T deter-
       mined by DGEBRD when reducing a real matrix A to bidiagonal form


SYNOPSIS
       SUBROUTINE DORGBR(VECT, M, N, K, A, LDA, TAU, WORK, LWORK, INFO)

       CHARACTER*1 VECT
       INTEGER M, N, K, LDA, LWORK, INFO
       DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)

       SUBROUTINE DORGBR_64(VECT, M, N, K, A, LDA, TAU, WORK, LWORK, INFO)

       CHARACTER*1 VECT
       INTEGER*8 M, N, K, LDA, LWORK, INFO
       DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)




   F95 INTERFACE
       SUBROUTINE ORGBR(VECT, M, N, K, A, LDA, TAU, WORK, LWORK,
              INFO)

       CHARACTER(LEN=1) :: VECT
       INTEGER :: M, N, K, LDA, LWORK, INFO
       REAL(8), DIMENSION(:) :: TAU, WORK
       REAL(8), DIMENSION(:,:) :: A

       SUBROUTINE ORGBR_64(VECT, M, N, K, A, LDA, TAU, WORK, LWORK,
              INFO)

       CHARACTER(LEN=1) :: VECT
       INTEGER(8) :: M, N, K, LDA, LWORK, INFO
       REAL(8), DIMENSION(:) :: TAU, WORK
       REAL(8), DIMENSION(:,:) :: A




   C INTERFACE
       #include <sunperf.h>

       void dorgbr(char vect, int m, int n, int k, double *a, int lda,  double
                 *tau, int *info);

       void  dorgbr_64(char vect, long m, long n, long k, double *a, long lda,
                 double *tau, long *info);



PURPOSE
       dorgbr generates one of the real orthogonal matrices Q or  P**T  deter-
       mined by DGEBRD when reducing a real matrix A to bidiagonal form: A = Q
       * B * P**T.  Q and P**T are defined as products of  elementary  reflec-
       tors H(i) or G(i) respectively.

       If  VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q is of
       order M:
       if m >= k, Q = H(1) H(2) . . . H(k) and DORGBR returns the first n col-
       umns of Q, where m >= n >= k;
       if  m < k, Q = H(1) H(2) . . . H(m-1) and DORGBR returns Q as an M-by-M
       matrix.

       If VECT = 'P', A is assumed to have been a K-by-N matrix, and  P**T  is
       of order N:
       if  k  <  n, P**T = G(k) . . . G(2) G(1) and DORGBR returns the first m
       rows of P**T, where n >= m >= k;
       if k >= n, P**T = G(n-1) . . . G(2) G(1) and DORGBR returns P**T as  an
       N-by-N matrix.


ARGUMENTS
       VECT (input)
                 Specifies  whether  the  matrix  Q  or  the  matrix  P**T  is
                 required, as defined in the transformation applied by DGEBRD:
                 = 'Q':  generate Q;
                 = 'P':  generate P**T.


       M (input) The number of rows of the matrix Q or P**T to be returned.  M
                 >= 0.


       N (input) The number of columns of the matrix Q or P**T to be returned.
                 N  >= 0.  If VECT = 'Q', M >= N >= min(M,K); if VECT = 'P', N
                 >= M >= min(N,K).


       K (input) If VECT = 'Q', the number of columns in the  original  M-by-K
                 matrix  reduced by DGEBRD.  If VECT = 'P', the number of rows
                 in the original K-by-N matrix reduced by DGEBRD.  K >= 0.


       A (input/output)
                 On entry, the vectors which define the elementary reflectors,
                 as returned by DGEBRD.  On exit, the M-by-N matrix Q or P**T.


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


       TAU (input)
                 (min(M,K)) if VECT = 'Q' (min(N,K)) if VECT = 'P' TAU(i) must
                 contain the scalar factor of the elementary reflector H(i) or
                 G(i), which determines Q or P**T, as returned  by  DGEBRD  in
                 its array argument TAUQ or TAUP.


       WORK (workspace)
                 On exit, if INFO = 0, WORK(1) returns the optimal LWORK.


       LWORK (input)
                 The  dimension  of  the array WORK. LWORK >= max(1,min(M,N)).
                 For optimum performance LWORK >= min(M,N)*NB, where NB is the
                 optimal blocksize.

                 If LWORK = -1, then a workspace query is assumed; the routine
                 only calculates the optimal size of the WORK  array,  returns
                 this value as the first entry of the WORK array, and no error
                 message related to LWORK is issued by XERBLA.


       INFO (output)
                 = 0:  successful exit
                 < 0:  if INFO = -i, the i-th argument had an illegal value




                                  7 Nov 2015                        dorgbr(3P)