dorgqr.f(3)

NAME
dorgqr.f -

SYNOPSIS

  Functions/Subroutines
subroutine dorgqr (M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
DORGQR

Function/Subroutine Documentation

  subroutine dorgqr (integerM, integerN, integerK, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )TAU, double precision, dimension( * )WORK, integerLWORK, integerINFO)

DORGQR

Purpose:

     DORGQR generates an M-by-N real matrix Q with orthonormal columns,
     which is defined as the first N columns of a product of K elementary
     reflectors of order M
           Q  =  H(1) H(2) . . . H(k)
     as returned by DGEQRF.

Parameters:
    M

              M is INTEGER
              The number of rows of the matrix Q. M >= 0.

    N

              N is INTEGER
              The number of columns of the matrix Q. M >= N >= 0.

    K

              K is INTEGER
              The number of elementary reflectors whose product defines the
              matrix Q. N >= K >= 0.

    A

              A is DOUBLE PRECISION array, dimension (LDA,N)
              On entry, the i-th column must contain the vector which
              defines the elementary reflector H(i), for i = 1,2,...,k, as
              returned by DGEQRF in the first k columns of its array
              argument A.
              On exit, the M-by-N matrix Q.

    LDA

              LDA is INTEGER
              The first dimension of the array A. LDA >= max(1,M).

    TAU

              TAU is DOUBLE PRECISION array, dimension (K)
              TAU(i) must contain the scalar factor of the elementary
              reflector H(i), as returned by DGEQRF.

    WORK

              WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
              On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

    LWORK

              LWORK is INTEGER
              The dimension of the array WORK. LWORK >= max(1,N).
              For optimum performance LWORK >= 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

              INFO is INTEGER
              = 0:  successful exit
              < 0:  if INFO = -i, the i-th argument has an illegal value

Author:
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Date:
    November 2011

Definition at line 129 of file dorgqr.f.

Author

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