TESTING/LIN/dqrt11.f(3) Library Functions Manual TESTING/LIN/dqrt11.f(3)

TESTING/LIN/dqrt11.f


double precision function dqrt11 (m, k, a, lda, tau, work, lwork)
DQRT11

DQRT11

Purpose:

!>
!> DQRT11 computes the test ratio
!>
!>       || Q'*Q - I || / (eps * m)
!>
!> where the orthogonal matrix Q is represented as a product of
!> elementary transformations.  Each transformation has the form
!>
!>    H(k) = I - tau(k) v(k) v(k)'
!>
!> where tau(k) is stored in TAU(k) and v(k) is an m-vector of the form
!> [ 0 ... 0 1 x(k) ]', where x(k) is a vector of length m-k stored
!> in A(k+1:m,k).
!> 

Parameters

M
!>          M is INTEGER
!>          The number of rows of the matrix A.
!> 

K

!>          K is INTEGER
!>          The number of columns of A whose subdiagonal entries
!>          contain information about orthogonal transformations.
!> 

A

!>          A is DOUBLE PRECISION array, dimension (LDA,K)
!>          The (possibly partial) output of a QR reduction routine.
!> 

LDA

!>          LDA is INTEGER
!>          The leading dimension of the array A.
!> 

TAU

!>          TAU is DOUBLE PRECISION array, dimension (K)
!>          The scaling factors tau for the elementary transformations as
!>          computed by the QR factorization routine.
!> 

WORK

!>          WORK is DOUBLE PRECISION array, dimension (LWORK)
!> 

LWORK

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

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 97 of file dqrt11.f.

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