DORGL2 (3lapack)

generate an m by n real matrix Q with orthonormal rows,

SYNOPSIS

  SUBROUTINE DORGL2( M, N, K, A, LDA, TAU, WORK, INFO )

      INTEGER        INFO, K, LDA, M, N

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

PURPOSE

  DORGL2 generates an m by n real matrix Q with orthonormal rows, which is
  defined as the first m rows of a product of k elementary reflectors of
  order n

        Q  =  H(k) . . . H(2) H(1)

  as returned by DGELQF.

ARGUMENTS

  M       (input) INTEGER
          The number of rows of the matrix Q. M >= 0.

  N       (input) INTEGER
          The number of columns of the matrix Q. N >= M.

  K       (input) INTEGER
          The number of elementary reflectors whose product defines the
          matrix Q. M >= K >= 0.

  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the i-th row must contain the vector which defines the
          elementary reflector H(i), for i = 1,2,...,k, as returned by DGELQF
          in the first k rows of its array argument A.  On exit, the m-by-n
          matrix Q.

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

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

  WORK    (workspace) DOUBLE PRECISION array, dimension (M)

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