dgeqpf.f(3)

NAME
dgeqpf.f -

SYNOPSIS

  Functions/Subroutines
subroutine dgeqpf (M, N, A, LDA, JPVT, TAU, WORK, INFO)
DGEQPF

Function/Subroutine Documentation

  subroutine dgeqpf (integerM, integerN, double precision, dimension( lda, * )A, integerLDA, integer, dimension( * )JPVT, double precision, dimension( * )TAU, double precision, dimension( * )WORK, integerINFO)

DGEQPF

Purpose:

     This routine is deprecated and has been replaced by routine DGEQP3.
     DGEQPF computes a QR factorization with column pivoting of a
     real M-by-N matrix A: A*P = Q*R.

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 DOUBLE PRECISION array, dimension (LDA,N)
              On entry, the M-by-N matrix A.
              On exit, the upper triangle of the array contains the
              min(M,N)-by-N upper triangular matrix R; the elements
              below the diagonal, together with the array TAU,
              represent the orthogonal matrix Q as a product of
              min(m,n) elementary reflectors.

    LDA

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

    JPVT

              JPVT is INTEGER array, dimension (N)
              On entry, if JPVT(i) .ne. 0, the i-th column of A is permuted
              to the front of A*P (a leading column); if JPVT(i) = 0,
              the i-th column of A is a free column.
              On exit, if JPVT(i) = k, then the i-th column of A*P
              was the k-th column of A.

    TAU

              TAU is DOUBLE PRECISION array, dimension (min(M,N))
              The scalar factors of the elementary reflectors.

    WORK

              WORK is DOUBLE PRECISION array, dimension (3*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 2011

Further Details:

      The matrix Q is represented as a product of elementary reflectors
         Q = H(1) H(2) . . . H(n)
      Each H(i) has the form
         H = I - tau * v * v**T
      where tau is a real scalar, and v is a real 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).
      The matrix P is represented in jpvt as follows: If
         jpvt(j) = i
      then the jth column of P is the ith canonical unit vector.
      Partial column norm updating strategy modified by
        Z. Drmac and Z. Bujanovic, Dept. of Mathematics,
        University of Zagreb, Croatia.
      -- April 2011                                                      --
      For more details see LAPACK Working Note 176.

Definition at line 143 of file dgeqpf.f.

Author

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