NAME¶

ZUNGR2 - generates an m by n complex matrix Q with orthonormal 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 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 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 vector 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 elementary 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 illegal value