zgelqt3.f

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

zgelqt3.f  

SYNOPSIS


 

Functions/Subroutines


recursive subroutine zgelqt3 (M, N, A, LDA, T, LDT, INFO)
ZGELQT3 recursively computes a LQ factorization of a general real or complex matrix using the compact WY representation of Q.  

Function/Subroutine Documentation

 

recursive subroutine zgelqt3 (integer M, integer N, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( ldt, * ) T, integer LDT, integer INFO)

ZGELQT3 recursively computes a LQ factorization of a general real or complex matrix using the compact WY representation of Q.

Purpose:

 DGELQT3 recursively computes a LQ factorization of a complex M-by-N
 matrix A, using the compact WY representation of Q.

 Based on the algorithm of Elmroth and Gustavson,
 IBM J. Res. Develop. Vol 44 No. 4 July 2000.


 

Parameters:

M

          M is INTEGER
          The number of rows of the matrix A.  M =< N.


N

          N is INTEGER
          The number of columns of the matrix A.  N >= 0.


A

          A is COMPLEX*16 array, dimension (LDA,N)
          On entry, the real M-by-N matrix A.  On exit, the elements on and
          below the diagonal contain the N-by-N lower triangular matrix L; the
          elements above the diagonal are the rows of V.  See below for
          further details.


LDA

          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,M).


T

          T is COMPLEX*16 array, dimension (LDT,N)
          The N-by-N upper triangular factor of the block reflector.
          The elements on and above the diagonal contain the block
          reflector T; the elements below the diagonal are not used.
          See below for further details.


LDT

          LDT is INTEGER
          The leading dimension of the array T.  LDT >= max(1,N).


INFO

          INFO is INTEGER
          = 0: successful exit
          < 0: if INFO = -i, the i-th argument had an illegal value


 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2017

Further Details:

  The matrix V stores the elementary reflectors H(i) in the i-th row
  above the diagonal. For example, if M=5 and N=3, the matrix V is

               V = (  1  v1 v1 v1 v1 )
                   (     1  v2 v2 v2 )
                   (     1  v3 v3 v3 )


  where the vi's represent the vectors which define H(i), which are returned
  in the matrix A.  The 1's along the diagonal of V are not stored in A.  The
  block reflector H is then given by

               H = I - V * T * V**T

  where V**T is the transpose of V.

  For details of the algorithm, see Elmroth and Gustavson (cited above).


 

Definition at line 133 of file zgelqt3.f.  

Author

Generated automatically by Doxygen for LAPACK from the source code.


 

Index

NAME
SYNOPSIS
Functions/Subroutines
Function/Subroutine Documentation
recursive subroutine zgelqt3 (integer M, integer N, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( ldt, * ) T, integer LDT, integer INFO)
Author