DORGR2(3)      LAPACK routine of NEC Numeric Library Collection      DORGR2(3)



NAME
       DORGR2

SYNOPSIS
       SUBROUTINE DORGR2 (M, N, K, A, LDA, TAU, WORK, INFO)



PURPOSE
            DORGR2 generates an m by n real matrix Q with orthonormal rows,
            which is defined as the last m rows of a product of k elementary
            reflectors of order n

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

            as returned by DGERQF.




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

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

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

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

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

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

           WORK      (output)
                     WORK is DOUBLE PRECISION array, dimension (M)

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



LAPACK routine                  31 October 2017                      DORGR2(3)