zgeqrt2.f man page

zgeqrt2.f

Synopsis

Functions/Subroutines

subroutine zgeqrt2 (M, N, A, LDA, T, LDT, INFO)
ZGEQRT2 computes a QR factorization of a general real or complex matrix using the compact WY representation of Q.

Function/Subroutine Documentation

subroutine zgeqrt2 (integer M, integer N, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( ldt, * ) T, integer LDT, integer INFO)

ZGEQRT2 computes a QR factorization of a general real or complex matrix using the compact WY representation of Q.  

Purpose:

 ZGEQRT2 computes a QR factorization of a complex M-by-N matrix A,
 using the compact WY representation of Q.
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 complex M-by-N matrix A.  On exit, the elements on and
          above the diagonal contain the N-by-N upper triangular matrix R; the
          elements below the diagonal are the columns 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:

December 2016

Further Details:

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

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

  where V**H is the conjugate transpose of V.

Definition at line 129 of file zgeqrt2.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page zgeqrt2(3) is an alias of zgeqrt2.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK