dqrt01.f - Man Page

subroutine dqrt01 (m, n, a, af, q, r, lda, tau, work, lwork, rwork, result)
DQRT01

DQRT01

Purpose:

 DQRT01 tests DGEQRF, which computes the QR factorization of an m-by-n
 matrix A, and partially tests DORGQR which forms the m-by-m
 orthogonal matrix Q.

 DQRT01 compares R with Q'*A, and checks that Q is orthogonal.

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)
          The m-by-n matrix A.

AF

          AF is DOUBLE PRECISION array, dimension (LDA,N)
          Details of the QR factorization of A, as returned by DGEQRF.
          See DGEQRF for further details.

Q

          Q is DOUBLE PRECISION array, dimension (LDA,M)
          The m-by-m orthogonal matrix Q.

R

          R is DOUBLE PRECISION array, dimension (LDA,max(M,N))

LDA

          LDA is INTEGER
          The leading dimension of the arrays A, AF, Q and R.
          LDA >= max(M,N).

TAU

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

WORK

          WORK is DOUBLE PRECISION array, dimension (LWORK)

LWORK

          LWORK is INTEGER
          The dimension of the array WORK.

RWORK

          RWORK is DOUBLE PRECISION array, dimension (M)

RESULT

          RESULT is DOUBLE PRECISION array, dimension (2)
          The test ratios:
          RESULT(1) = norm( R - Q'*A ) / ( M * norm(A) * EPS )
          RESULT(2) = norm( I - Q'*Q ) / ( M * EPS )

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 124 of file dqrt01.f.