SRC/zgeqr2p.f(3)           Library Functions Manual           SRC/zgeqr2p.f(3)

NAME
       SRC/zgeqr2p.f

SYNOPSIS
   Functions/Subroutines
       subroutine zgeqr2p (m, n, a, lda, tau, work, info)
           ZGEQR2P computes the QR factorization of a general rectangular
           matrix with non-negative diagonal elements using an unblocked
           algorithm.

Function/Subroutine Documentation
   subroutine zgeqr2p (integer m, integer n, complex*16, dimension( lda, * )
       a, integer lda, complex*16, dimension( * ) tau, complex*16, dimension(
       * ) work, integer info)
       ZGEQR2P computes the QR factorization of a general rectangular matrix
       with non-negative diagonal elements using an unblocked algorithm.

       Purpose:


            ZGEQR2P computes a QR factorization of a complex m-by-n matrix A:

               A = Q * ( R ),
                       ( 0 )

            where:

               Q is a m-by-m orthogonal matrix;
               R is an upper-triangular n-by-n matrix with nonnegative diagonal
               entries;
               0 is a (m-n)-by-n zero matrix, if m > n.

       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 >= 0.

           A

                     A is COMPLEX*16 array, dimension (LDA,N)
                     On entry, the m by n matrix A.
                     On exit, the elements on and above the diagonal of the array
                     contain the min(m,n) by n upper trapezoidal matrix R (R is
                     upper triangular if m >= n). The diagonal entries of R
                     are real and nonnegative; the elements below the diagonal,
                     with the array TAU, represent the unitary matrix Q as a
                     product of elementary reflectors (see Further Details).

           LDA

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

           TAU

                     TAU is COMPLEX*16 array, dimension (min(M,N))
                     The scalar factors of the elementary reflectors (see Further
                     Details).

           WORK

                     WORK is COMPLEX*16 array, dimension (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.

       Further Details:


             The matrix Q is represented as a product of elementary reflectors

                Q = H(1) H(2) . . . H(k), where k = min(m,n).

             Each H(i) has the form

                H(i) = I - tau * v * v**H

             where tau is a complex scalar, and v is a complex vector with
             v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i),
             and tau in TAU(i).

            See Lapack Working Note 203 for details

       Definition at line 133 of file zgeqr2p.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0                SRC/zgeqr2p.f(3)