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zungr2.f(3) LAPACK zungr2.f(3)

NAME

zungr2.f -

SYNOPSIS

Functions/Subroutines


subroutine zungr2 (M, N, K, A, LDA, TAU, WORK, INFO)
 
ZUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).

Function/Subroutine Documentation

subroutine zungr2 (integerM, integerN, integerK, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( * )TAU, complex*16, dimension( * )WORK, integerINFO)

ZUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).
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 H(2)**H . . . H(k)**H
as returned by ZGERQF.
Parameters:
M
          M is INTEGER
          The number of rows of the matrix Q. M >= 0.
N
          N is INTEGER
          The number of columns of the matrix Q. N >= M.
K
          K is INTEGER
          The number of elementary reflectors whose product defines the
          matrix Q. M >= K >= 0.
A
          A is 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
          LDA is INTEGER
          The first dimension of the array A. LDA >= max(1,M).
TAU
          TAU is COMPLEX*16 array, dimension (K)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by ZGERQF.
WORK
          WORK is COMPLEX*16 array, dimension (M)
INFO
          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:
September 2012
Definition at line 115 of file zungr2.f.

Author

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