LAPACK  3.5.0
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cungr2.f File Reference

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Functions/Subroutines

subroutine cungr2 (M, N, K, A, LDA, TAU, WORK, INFO)
 CUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).

Function/Subroutine Documentation

subroutine cungr2 ( integer  M,
integer  N,
integer  K,
complex, dimension( lda, * )  A,
integer  LDA,
complex, dimension( * )  TAU,
complex, dimension( * )  WORK,
integer  INFO 
)

CUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).

Download CUNGR2 + dependencies [TGZ] [ZIP] [TXT]
Purpose:
 CUNGR2 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
[in]M
          M is INTEGER
          The number of rows of the matrix Q. M >= 0.
[in]N
          N is INTEGER
          The number of columns of the matrix Q. N >= M.
[in]K
          K is INTEGER
          The number of elementary reflectors whose product defines the
          matrix Q. M >= K >= 0.
[in,out]A
          A is COMPLEX 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 CGERQF in the last k rows of its array argument
          A.
          On exit, the m-by-n matrix Q.
[in]LDA
          LDA is INTEGER
          The first dimension of the array A. LDA >= max(1,M).
[in]TAU
          TAU is COMPLEX array, dimension (K)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by CGERQF.
[out]WORK
          WORK is COMPLEX array, dimension (M)
[out]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 cungr2.f.

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