CUNGRQ (3) Linux Manual Page
cungrq.f –
Synopsis
Functions/Subroutines
subroutine cungrq (M, N, K, A, LDA, TAU, WORK, LWORK, INFO)CUNGRQ
Function/Subroutine Documentation
subroutine cungrq (integerM, integerN, integerK, complex, dimension( lda, * )A, integerLDA, complex, dimension( * )TAU, complex, dimension( * )WORK, integerLWORK, integerINFO)
CUNGRQ Purpose:
CUNGRQ 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 H(2)**H . . . H(k)**H
as returned by CGERQF.
Parameters:
- M
M is INTEGER
N
The number of rows of the matrix Q. M >= 0.N is INTEGER
K
The number of columns of the matrix Q. N >= M.K is INTEGER
A
The number of elementary reflectors whose product defines the
matrix Q. M >= K >= 0.A is COMPLEX array, dimension (LDA,N)
LDA
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 CGERQF in the last k rows of its array argument
A.
On exit, the M-by-N matrix Q.LDA is INTEGER
TAU
The first dimension of the array A. LDA >= max(1,M).TAU is COMPLEX array, dimension (K)
WORK
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by CGERQF.WORK is COMPLEX array, dimension (MAX(1,LWORK))
LWORK
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.LWORK is INTEGER
INFO
The dimension of the array WORK. LWORK >= max(1,M).
For optimum performance LWORK >= M*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, returns
this value as the first entry of the WORK array, and no error
message related to LWORK is issued by XERBLA.INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value
Author:
- Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
- November 2011
Definition at line 129 of file cungrq.f.