dqrt03.f - Man Page

subroutine dqrt03 (m, n, k, af, c, cc, q, lda, tau, work, lwork, rwork, result)
DQRT03

DQRT03

Purpose:

 DQRT03 tests DORMQR, which computes Q*C, Q'*C, C*Q or C*Q'.

 DQRT03 compares the results of a call to DORMQR with the results of
 forming Q explicitly by a call to DORGQR and then performing matrix
 multiplication by a call to DGEMM.

Parameters

M

          M is INTEGER
          The order of the orthogonal matrix Q.  M >= 0.

N

          N is INTEGER
          The number of rows or columns of the matrix C; C is m-by-n if
          Q is applied from the left, or n-by-m if Q is applied from
          the right.  N >= 0.

K

          K is INTEGER
          The number of elementary reflectors whose product defines the
          orthogonal matrix Q.  M >= K >= 0.

AF

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

C

          C is DOUBLE PRECISION array, dimension (LDA,N)

CC

          CC is DOUBLE PRECISION array, dimension (LDA,N)

Q

          Q is DOUBLE PRECISION array, dimension (LDA,M)

LDA

          LDA is INTEGER
          The leading dimension of the arrays AF, C, CC, and Q.

TAU

          TAU is DOUBLE PRECISION array, dimension (min(M,N))
          The scalar factors of the elementary reflectors corresponding
          to the QR factorization in AF.

WORK

          WORK is DOUBLE PRECISION array, dimension (LWORK)

LWORK

          LWORK is INTEGER
          The length of WORK.  LWORK must be at least M, and should be
          M*NB, where NB is the blocksize for this environment.

RWORK

          RWORK is DOUBLE PRECISION array, dimension (M)

RESULT

          RESULT is DOUBLE PRECISION array, dimension (4)
          The test ratios compare two techniques for multiplying a
          random matrix C by an m-by-m orthogonal matrix Q.
          RESULT(1) = norm( Q*C - Q*C )  / ( M * norm(C) * EPS )
          RESULT(2) = norm( C*Q - C*Q )  / ( M * norm(C) * EPS )
          RESULT(3) = norm( Q'*C - Q'*C )/ ( M * norm(C) * EPS )
          RESULT(4) = norm( C*Q' - C*Q' )/ ( M * norm(C) * EPS )

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 134 of file dqrt03.f.