ZUNM2L(3)      LAPACK routine of NEC Numeric Library Collection      ZUNM2L(3)



NAME
       ZUNM2L

SYNOPSIS
       SUBROUTINE ZUNM2L (SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK,
           INFO)



PURPOSE
            ZUNM2L overwrites the general complex m-by-n matrix C with

                  Q * C  if SIDE = 'L' and TRANS = 'N', or

                  Q**H* C  if SIDE = 'L' and TRANS = 'C', or

                  C * Q  if SIDE = 'R' and TRANS = 'N', or

                  C * Q**H if SIDE = 'R' and TRANS = 'C',

            where Q is a complex unitary matrix defined as the product of k
            elementary reflectors

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

            as returned by ZGEQLF. Q is of order m if SIDE = 'L' and of order n
            if SIDE = 'R'.




ARGUMENTS
           SIDE      (input)
                     SIDE is CHARACTER*1
                     = 'L': apply Q or Q**H from the Left
                     = 'R': apply Q or Q**H from the Right

           TRANS     (input)
                     TRANS is CHARACTER*1
                     = 'N': apply Q  (No transpose)
                     = 'C': apply Q**H (Conjugate transpose)

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

           N         (input)
                     N is INTEGER
                     The number of columns of the matrix C. N >= 0.

           K         (input)
                     K is INTEGER
                     The number of elementary reflectors whose product defines
                     the matrix Q.
                     If SIDE = 'L', M >= K >= 0;
                     if SIDE = 'R', N >= K >= 0.

           A         (input)
                     A is COMPLEX*16 array, dimension (LDA,K)
                     The i-th column must contain the vector which defines the
                     elementary reflector H(i), for i = 1,2,...,k, as returned by
                     ZGEQLF in the last k columns of its array argument A.
                     A is modified by the routine but restored on exit.

           LDA       (input)
                     LDA is INTEGER
                     The leading dimension of the array A.
                     If SIDE = 'L', LDA >= max(1,M);
                     if SIDE = 'R', LDA >= max(1,N).

           TAU       (input)
                     TAU is COMPLEX*16 array, dimension (K)
                     TAU(i) must contain the scalar factor of the elementary
                     reflector H(i), as returned by ZGEQLF.

           C         (input/output)
                     C is COMPLEX*16 array, dimension (LDC,N)
                     On entry, the m-by-n matrix C.
                     On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.

           LDC       (input)
                     LDC is INTEGER
                     The leading dimension of the array C. LDC >= max(1,M).

           WORK      (output)
                     WORK is COMPLEX*16 array, dimension
                                              (N) if SIDE = 'L',
                                              (M) if SIDE = 'R'

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



LAPACK routine                  31 October 2017                      ZUNM2L(3)