sqrt01.f - Man Page

subroutine sqrt01 (m, n, a, af, q, r, lda, tau, work, lwork, rwork, result)
SQRT01

SQRT01

Purpose:

 SQRT01 tests SGEQRF, which computes the QR factorization of an m-by-n
 matrix A, and partially tests SORGQR which forms the m-by-m
 orthogonal matrix Q.

 SQRT01 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 REAL array, dimension (LDA,N)
          The m-by-n matrix A.

AF

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

Q

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

R

          R is REAL 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 REAL array, dimension (min(M,N))
          The scalar factors of the elementary reflectors, as returned
          by SGEQRF.

WORK

          WORK is REAL array, dimension (LWORK)

LWORK

          LWORK is INTEGER
          The dimension of the array WORK.

RWORK

          RWORK is REAL array, dimension (M)

RESULT

          RESULT is REAL 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 sqrt01.f.