ctzrzf.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
Page Index
 

NAME

ctzrzf.f  

SYNOPSIS


 

Functions/Subroutines


subroutine ctzrzf (M, N, A, LDA, TAU, WORK, LWORK, INFO)
CTZRZF  

Function/Subroutine Documentation

 

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

CTZRZF

Purpose:

 CTZRZF reduces the M-by-N ( M<=N ) complex upper trapezoidal matrix A
 to upper triangular form by means of unitary transformations.

 The upper trapezoidal matrix A is factored as

    A = ( R  0 ) * Z,

 where Z is an N-by-N unitary matrix and R is an M-by-M upper
 triangular matrix.


 

Parameters:

M

          M is INTEGER
          The number of rows of the matrix A.  M >= 0.


N

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


A

          A is COMPLEX array, dimension (LDA,N)
          On entry, the leading M-by-N upper trapezoidal part of the
          array A must contain the matrix to be factorized.
          On exit, the leading M-by-M upper triangular part of A
          contains the upper triangular matrix R, and elements M+1 to
          N of the first M rows of A, with the array TAU, represent the
          unitary matrix Z as a product of M elementary reflectors.


LDA

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


TAU

          TAU is COMPLEX array, dimension (M)
          The scalar factors of the elementary reflectors.


WORK

          WORK is COMPLEX 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 had an illegal value


 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

April 2012

Contributors:

A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

Further Details:

  The N-by-N matrix Z can be computed by

     Z =  Z(1)*Z(2)* ... *Z(M)

  where each N-by-N Z(k) is given by

     Z(k) = I - tau(k)*v(k)*v(k)**H

  with v(k) is the kth row vector of the M-by-N matrix

     V = ( I   A(:,M+1:N) )

  I is the M-by-M identity matrix, A(:,M+1:N)
  is the output stored in A on exit from DTZRZF,
  and tau(k) is the kth element of the array TAU.


 

Definition at line 153 of file ctzrzf.f.  

Author

Generated automatically by Doxygen for LAPACK from the source code.


 

Index

NAME
SYNOPSIS
Functions/Subroutines
Function/Subroutine Documentation
subroutine ctzrzf (integer M, integer N, complex, dimension( lda, * ) A, integer LDA, complex, dimension( * ) TAU, complex, dimension( * ) WORK, integer LWORK, integer INFO)
Author
LinuxReviews : manual page archive : man3