◆ zungqr()

Generates matrix Q of QR factorization of a complex matrix

Purpose: This routine generates an m x 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 zgeqrf.

Parameters

[in]	m	Number of rows of the matrix A. (m >= 0)
[in]	n	Number of columns of the matrix A. (m >= n >= 0) (If n = 0, returns without computation)
[in]	k	Number of elementary reflectors whose product defines the matrix Q. (n >= k >= 0)
[in]	lda	Leading dimension of the two dimensional array a[][]. (lda >= max(1, m))
[in,out]	a[][]	Array a[la][lda] (la >= n) [in] The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1, 2, ..., k, as returned by zgeqrf in the first k columns of its array argument a[][]. [out] m x n matrix Q.
[in]	tau[]	Array tau[ltau] (ltau >= k) The scalar factors of the elementary reflectors H(i) as returned by zgeqrf.
[out]	work[]	Array work[lwork] Work array. On exit, if info = 0, work[0] returns the optimal lwork.
[in]	lwork	The dimension of the array work[]. (lwork >= max(1, n)) For optimal performance lwork >= n*nb, where nb is the optimal blocksize. If lwork = -1, then a workspace query is assumed. The routine only calculates the optimal size of the work[] array, and returns the value in work[0].
[out]	info	= 0: Successful exit = -1: The argument m had an illegal value (m < 0) = -2: The argument n had an illegal value (n < 0 or n > m) = -3: The argument k had an illegal value (k < 0 or k > n) = -4: The argument lda had an illegal value (lda < max(1, m)) = -8: The argument lwork had an illegal value (lwork too small)