dorgbr man page on YellowDog

Man page or keyword search:  
man Server   18644 pages
apropos Keyword Search (all sections)
Output format
YellowDog logo
[printable version]

DORGBR(l)			       )			     DORGBR(l)

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	  VECT

	   INTEGER	  INFO, K, LDA, LWORK, M, N

	   DOUBLE	  PRECISION A( LDA, * ), TAU( * ), WORK( * )

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 reflectors
       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) CHARACTER*1
	       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) INTEGER
	       The number of rows of the matrix Q or P**T to be	 returned.   M
	       >= 0.

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

       TAU     (input) DOUBLE PRECISION array, dimension
	       (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/output) DOUBLE PRECISION array, dimension (LWORK)
	       On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

       LWORK   (input) INTEGER
	       The dimension of the array WORK. LWORK >= max(1,min(M,N)).  For
	       optimum performance LWORK >= min(M,N)*NB, where NB is the opti‐
	       mal 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) INTEGER
	       = 0:  successful exit
	       < 0:  if INFO = -i, the i-th argument had an illegal value

LAPACK version 3.0		 15 June 2000			     DORGBR(l)
[top]

List of man pages available for YellowDog

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net