*> \brief \b SLQT02 * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE SLQT02( M, N, K, A, AF, Q, L, LDA, TAU, WORK, LWORK, * RWORK, RESULT ) * * .. Scalar Arguments .. * INTEGER K, LDA, LWORK, M, N * .. * .. Array Arguments .. * REAL A( LDA, * ), AF( LDA, * ), L( LDA, * ), * $ Q( LDA, * ), RESULT( * ), RWORK( * ), TAU( * ), * $ WORK( LWORK ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> SLQT02 tests SORGLQ, 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, SLQT02 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. *> \endverbatim * * Arguments: * ========== * *> \param[in] M *> \verbatim *> M is INTEGER *> The number of rows of the matrix Q to be generated. M >= 0. *> \endverbatim *> *> \param[in] N *> \verbatim *> N is INTEGER *> The number of columns of the matrix Q to be generated. *> N >= M >= 0. *> \endverbatim *> *> \param[in] K *> \verbatim *> K is INTEGER *> The number of elementary reflectors whose product defines the *> matrix Q. M >= K >= 0. *> \endverbatim *> *> \param[in] A *> \verbatim *> A is REAL array, dimension (LDA,N) *> The m-by-n matrix A which was factorized by SLQT01. *> \endverbatim *> *> \param[in] AF *> \verbatim *> AF is REAL array, dimension (LDA,N) *> Details of the LQ factorization of A, as returned by SGELQF. *> See SGELQF for further details. *> \endverbatim *> *> \param[out] Q *> \verbatim *> Q is REAL array, dimension (LDA,N) *> \endverbatim *> *> \param[out] L *> \verbatim *> L is REAL array, dimension (LDA,M) *> \endverbatim *> *> \param[in] LDA *> \verbatim *> LDA is INTEGER *> The leading dimension of the arrays A, AF, Q and L. LDA >= N. *> \endverbatim *> *> \param[in] TAU *> \verbatim *> TAU is REAL array, dimension (M) *> The scalar factors of the elementary reflectors corresponding *> to the LQ factorization in AF. *> \endverbatim *> *> \param[out] WORK *> \verbatim *> WORK is REAL array, dimension (LWORK) *> \endverbatim *> *> \param[in] LWORK *> \verbatim *> LWORK is INTEGER *> The dimension of the array WORK. *> \endverbatim *> *> \param[out] RWORK *> \verbatim *> RWORK is REAL array, dimension (M) *> \endverbatim *> *> \param[out] RESULT *> \verbatim *> RESULT is REAL array, dimension (2) *> The test ratios: *> RESULT(1) = norm( L - A*Q' ) / ( N * norm(A) * EPS ) *> RESULT(2) = norm( I - Q*Q' ) / ( N * EPS ) *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup single_lin * * ===================================================================== SUBROUTINE SLQT02( M, N, K, A, AF, Q, L, LDA, TAU, WORK, LWORK, $ RWORK, RESULT ) * * -- LAPACK test routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. INTEGER K, LDA, LWORK, M, N * .. * .. Array Arguments .. REAL A( LDA, * ), AF( LDA, * ), L( LDA, * ), $ Q( LDA, * ), RESULT( * ), RWORK( * ), TAU( * ), $ WORK( LWORK ) * .. * * ===================================================================== * * .. Parameters .. REAL ZERO, ONE PARAMETER ( ZERO = 0.0E+0, ONE = 1.0E+0 ) REAL ROGUE PARAMETER ( ROGUE = -1.0E+10 ) * .. * .. Local Scalars .. INTEGER INFO REAL ANORM, EPS, RESID * .. * .. External Functions .. REAL SLAMCH, SLANGE, SLANSY EXTERNAL SLAMCH, SLANGE, SLANSY * .. * .. External Subroutines .. EXTERNAL SGEMM, SLACPY, SLASET, SORGLQ, SSYRK * .. * .. Intrinsic Functions .. INTRINSIC MAX, REAL * .. * .. Scalars in Common .. CHARACTER*32 SRNAMT * .. * .. Common blocks .. COMMON / SRNAMC / SRNAMT * .. * .. Executable Statements .. * EPS = SLAMCH( 'Epsilon' ) * * Copy the first k rows of the factorization to the array Q * CALL SLASET( 'Full', M, N, ROGUE, ROGUE, Q, LDA ) CALL SLACPY( 'Upper', K, N-1, AF( 1, 2 ), LDA, Q( 1, 2 ), LDA ) * * Generate the first n columns of the matrix Q * SRNAMT = 'SORGLQ' CALL SORGLQ( M, N, K, Q, LDA, TAU, WORK, LWORK, INFO ) * * Copy L(1:k,1:m) * CALL SLASET( 'Full', K, M, ZERO, ZERO, L, LDA ) CALL SLACPY( 'Lower', K, M, AF, LDA, L, LDA ) * * Compute L(1:k,1:m) - A(1:k,1:n) * Q(1:m,1:n)' * CALL SGEMM( 'No transpose', 'Transpose', K, M, N, -ONE, A, LDA, Q, $ LDA, ONE, L, LDA ) * * Compute norm( L - A*Q' ) / ( N * norm(A) * EPS ) . * ANORM = SLANGE( '1', K, N, A, LDA, RWORK ) RESID = SLANGE( '1', K, M, L, LDA, RWORK ) IF( ANORM.GT.ZERO ) THEN RESULT( 1 ) = ( ( RESID / REAL( MAX( 1, N ) ) ) / ANORM ) / EPS ELSE RESULT( 1 ) = ZERO END IF * * Compute I - Q*Q' * CALL SLASET( 'Full', M, M, ZERO, ONE, L, LDA ) CALL SSYRK( 'Upper', 'No transpose', M, N, -ONE, Q, LDA, ONE, L, $ LDA ) * * Compute norm( I - Q*Q' ) / ( N * EPS ) . * RESID = SLANSY( '1', 'Upper', M, L, LDA, RWORK ) * RESULT( 2 ) = ( RESID / REAL( MAX( 1, N ) ) ) / EPS * RETURN * * End of SLQT02 * END