SRC/dgeqrt2.f(3)           Library Functions Manual           SRC/dgeqrt2.f(3)

NAME
       SRC/dgeqrt2.f

SYNOPSIS
   Functions/Subroutines
       subroutine dgeqrt2 (m, n, a, lda, t, ldt, info)
           DGEQRT2 computes a QR factorization of a general real or complex
           matrix using the compact WY representation of Q.

Function/Subroutine Documentation
   subroutine dgeqrt2 (integer m, integer n, double precision, dimension( lda,
       * ) a, integer lda, double precision, dimension( ldt, * ) t, integer
       ldt, integer info)
       DGEQRT2 computes a QR factorization of a general real or complex matrix
       using the compact WY representation of Q.

       Purpose:


            DGEQRT2 computes a QR factorization of a real 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 DOUBLE PRECISION array, dimension (LDA,N)
                     On entry, the real 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 DOUBLE PRECISION 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.

       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**T

             where V**T is the transpose of V.

       Definition at line 126 of file dgeqrt2.f.

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

LAPACK                          Version 3.12.0                SRC/dgeqrt2.f(3)