sqrt03.f - Man Page

subroutine sqrt03 (m, n, k, af, c, cc, q, lda, tau, work, lwork, rwork, result)
SQRT03

SQRT03

Purpose:

 SQRT03 tests SORMQR, which computes Q*C, Q'*C, C*Q or C*Q'.

 SQRT03 compares the results of a call to SORMQR with the results of
 forming Q explicitly by a call to SORGQR and then performing matrix
 multiplication by a call to SGEMM.

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 REAL array, dimension (LDA,N)
          Details of the QR factorization of an m-by-n matrix, as
          returned by SGEQRF. See SGEQRF for further details.

C

          C is REAL array, dimension (LDA,N)

CC

          CC is REAL array, dimension (LDA,N)

Q

          Q is REAL array, dimension (LDA,M)

LDA

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

TAU

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

WORK

          WORK is REAL 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 REAL array, dimension (M)

RESULT

          RESULT is REAL 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 sqrt03.f.