LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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◆ dlqt02()

subroutine dlqt02 ( integer  m,
integer  n,
integer  k,
double precision, dimension( lda, * )  a,
double precision, dimension( lda, * )  af,
double precision, dimension( lda, * )  q,
double precision, dimension( lda, * )  l,
integer  lda,
double precision, dimension( * )  tau,
double precision, dimension( lwork )  work,
integer  lwork,
double precision, dimension( * )  rwork,
double precision, dimension( * )  result 
)

DLQT02

Purpose:
 DLQT02 tests DORGLQ, which generates an m-by-n matrix Q with
 orthonornmal rows that is defined as the product of k elementary
 reflectors.

 Given the LQ factorization of an m-by-n matrix A, DLQT02 generates
 the orthogonal matrix Q defined by the factorization of the first k
 rows of A; it compares L(1:k,1:m) with A(1:k,1:n)*Q(1:m,1:n)', and
 checks that the rows of Q are orthonormal.
Parameters
[in]M
          M is INTEGER
          The number of rows of the matrix Q to be generated.  M >= 0.
[in]N
          N is INTEGER
          The number of columns of the matrix Q to be generated.
          N >= M >= 0.
[in]K
          K is INTEGER
          The number of elementary reflectors whose product defines the
          matrix Q. M >= K >= 0.
[in]A
          A is DOUBLE PRECISION array, dimension (LDA,N)
          The m-by-n matrix A which was factorized by DLQT01.
[in]AF
          AF is DOUBLE PRECISION array, dimension (LDA,N)
          Details of the LQ factorization of A, as returned by DGELQF.
          See DGELQF for further details.
[out]Q
          Q is DOUBLE PRECISION array, dimension (LDA,N)
[out]L
          L is DOUBLE PRECISION array, dimension (LDA,M)
[in]LDA
          LDA is INTEGER
          The leading dimension of the arrays A, AF, Q and L. LDA >= N.
[in]TAU
          TAU is DOUBLE PRECISION array, dimension (M)
          The scalar factors of the elementary reflectors corresponding
          to the LQ factorization in AF.
[out]WORK
          WORK is DOUBLE PRECISION array, dimension (LWORK)
[in]LWORK
          LWORK is INTEGER
          The dimension of the array WORK.
[out]RWORK
          RWORK is DOUBLE PRECISION array, dimension (M)
[out]RESULT
          RESULT is DOUBLE PRECISION array, dimension (2)
          The test ratios:
          RESULT(1) = norm( L - A*Q' ) / ( N * norm(A) * EPS )
          RESULT(2) = norm( I - Q*Q' ) / ( N * EPS )
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.