DORGL2(3)      LAPACK routine of NEC Numeric Library Collection      DORGL2(3)



NAME
       DORGL2

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



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)
                     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 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)
                     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 DGELQF.

           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                      DORGL2(3)