zungr2(3)

NAME

ZUNGR2 - generate an m by n complex matrix Q with or

thonormal rows,

SYNOPSIS

SUBROUTINE ZUNGR2( M, N, K, A, LDA, TAU, WORK, INFO )
    INTEGER        INFO, K, LDA, M, N
    COMPLEX*16     A( LDA, * ), TAU( * ), WORK( * )

PURPOSE

ZUNGR2 generates an m by n complex matrix Q with orthonor

mal 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 ZGERQF.

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) COMPLEX*16 array, dimension (LDA,N)

On entry, the (m-k+i)-th row must contain the vec

tor which defines the elementary reflector H(i), for i =

1,2,...,k, as returned by ZGERQF in the last 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) COMPLEX*16 array, dimension (K)

TAU(i) must contain the scalar factor of the ele

mentary reflector H(i), as returned by ZGERQF.

WORK (workspace) COMPLEX*16 array, dimension (M)

INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = -i, the i-th argument has an ille

gal value

LAPACK version 3.0 15 June 2000

ZUNGR2(3)