zungrq.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
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NAME

zungrq.f  

SYNOPSIS


 

Functions/Subroutines


subroutine zungrq (M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
ZUNGRQ  

Function/Subroutine Documentation

 

subroutine zungrq (integer M, integer N, integer K, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( * ) TAU, complex*16, dimension( * ) WORK, integer LWORK, integer INFO)

ZUNGRQ

Purpose:

 ZUNGRQ 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 (MAX(1,LWORK))
          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.


LWORK

          LWORK is INTEGER
          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

          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:

December 2016

Definition at line 130 of file zungrq.f.  

Author

Generated automatically by Doxygen for LAPACK from the source code.


 

Index

NAME
SYNOPSIS
Functions/Subroutines
Function/Subroutine Documentation
subroutine zungrq (integer M, integer N, integer K, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( * ) TAU, complex*16, dimension( * ) WORK, integer LWORK, integer INFO)
Author