CUNG2R(3)      LAPACK routine of NEC Numeric Library Collection      CUNG2R(3)



NAME
       CUNG2R

SYNOPSIS
       SUBROUTINE CUNG2R (M, N, K, A, LDA, TAU, WORK, INFO)



PURPOSE
            CUNG2R generates an m by n complex 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 CGEQRF.




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. M >= N >= 0.

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

           A         (input/output)
                     A is COMPLEX 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 CGEQRF in the first k columns 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 COMPLEX array, dimension (K)
                     TAU(i) must contain the scalar factor of the elementary
                     reflector H(i), as returned by CGEQRF.

           WORK      (output)
                     WORK is COMPLEX array, dimension (N)

           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                      CUNG2R(3)