Previous: dorghr Up: ../lapack-d.html Next: dorglq

dorgl2

 NAME
      DORGL2 - 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 elemen-
              tary 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