dqpt01.f - Man Page

double precision function dqpt01 (m, n, k, a, af, lda, tau, jpvt, work, lwork)
DQPT01

DQPT01

Purpose:

 DQPT01 tests the QR-factorization with pivoting of a matrix A.  The
 array AF contains the (possibly partial) QR-factorization of A, where
 the upper triangle of AF(1:K,1:K) is a partial triangular factor,
 the entries below the diagonal in the first K columns are the
 Householder vectors, and the rest of AF contains a partially updated
 matrix.

 This function returns ||A*P - Q*R|| / ( ||norm(A)||*eps*max(M,N) ),
 where || . || is matrix one norm.

Parameters

M

          M is INTEGER
          The number of rows of the matrices A and AF.

N

          N is INTEGER
          The number of columns of the matrices A and AF.

K

          K is INTEGER
          The number of columns of AF that have been reduced
          to upper triangular form.

A

          A is DOUBLE PRECISION array, dimension (LDA, N)
          The original matrix A.

AF

          AF is DOUBLE PRECISION array, dimension (LDA,N)
          The (possibly partial) output of DGEQPF.  The upper triangle
          of AF(1:k,1:k) is a partial triangular factor, the entries
          below the diagonal in the first k columns are the Householder
          vectors, and the rest of AF contains a partially updated
          matrix.

LDA

          LDA is INTEGER
          The leading dimension of the arrays A and AF.

TAU

          TAU is DOUBLE PRECISION array, dimension (K)
          Details of the Householder transformations as returned by
          DGEQPF.

JPVT

          JPVT is INTEGER array, dimension (N)
          Pivot information as returned by DGEQPF.

WORK

          WORK is DOUBLE PRECISION array, dimension (LWORK)

LWORK

          LWORK is INTEGER
          The length of the array WORK.  LWORK >= M*N+N.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 119 of file dqpt01.f.