*> \brief \b SRQT02 * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE SRQT02( M, N, K, A, AF, Q, R, LDA, TAU, WORK, LWORK, * RWORK, RESULT ) * * .. Scalar Arguments .. * INTEGER K, LDA, LWORK, M, N * .. * .. Array Arguments .. * REAL A( LDA, * ), AF( LDA, * ), Q( LDA, * ), * $ R( LDA, * ), RESULT( * ), RWORK( * ), TAU( * ), * $ WORK( LWORK ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> SRQT02 tests SORGRQ, which generates an m-by-n matrix Q with *> orthonornmal rows that is defined as the product of k elementary *> reflectors. *> *> Given the RQ factorization of an m-by-n matrix A, SRQT02 generates *> the orthogonal matrix Q defined by the factorization of the last k *> rows of A; it compares R(m-k+1:m,n-m+1:n) with *> A(m-k+1:m,1:n)*Q(n-m+1:n,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 SRQT01. *> \endverbatim *> *> \param[in] AF *> \verbatim *> AF is REAL array, dimension (LDA,N) *> Details of the RQ factorization of A, as returned by SGERQF. *> See SGERQF for further details. *> \endverbatim *> *> \param[out] Q *> \verbatim *> Q is REAL array, dimension (LDA,N) *> \endverbatim *> *> \param[out] R *> \verbatim *> R 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 RQ 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( R - 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 SRQT02( M, N, K, A, AF, Q, R, 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, * ), Q( LDA, * ), $ R( 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, SORGRQ, SSYRK * .. * .. Intrinsic Functions .. INTRINSIC MAX, REAL * .. * .. Scalars in Common .. CHARACTER*32 SRNAMT * .. * .. Common blocks .. COMMON / SRNAMC / SRNAMT * .. * .. Executable Statements .. * * Quick return if possible * IF( M.EQ.0 .OR. N.EQ.0 .OR. K.EQ.0 ) THEN RESULT( 1 ) = ZERO RESULT( 2 ) = ZERO RETURN END IF * EPS = SLAMCH( 'Epsilon' ) * * Copy the last k rows of the factorization to the array Q * CALL SLASET( 'Full', M, N, ROGUE, ROGUE, Q, LDA ) IF( K.LT.N ) $ CALL SLACPY( 'Full', K, N-K, AF( M-K+1, 1 ), LDA, $ Q( M-K+1, 1 ), LDA ) IF( K.GT.1 ) $ CALL SLACPY( 'Lower', K-1, K-1, AF( M-K+2, N-K+1 ), LDA, $ Q( M-K+2, N-K+1 ), LDA ) * * Generate the last n rows of the matrix Q * SRNAMT = 'SORGRQ' CALL SORGRQ( M, N, K, Q, LDA, TAU( M-K+1 ), WORK, LWORK, INFO ) * * Copy R(m-k+1:m,n-m+1:n) * CALL SLASET( 'Full', K, M, ZERO, ZERO, R( M-K+1, N-M+1 ), LDA ) CALL SLACPY( 'Upper', K, K, AF( M-K+1, N-K+1 ), LDA, $ R( M-K+1, N-K+1 ), LDA ) * * Compute R(m-k+1:m,n-m+1:n) - A(m-k+1:m,1:n) * Q(n-m+1:n,1:n)' * CALL SGEMM( 'No transpose', 'Transpose', K, M, N, -ONE, $ A( M-K+1, 1 ), LDA, Q, LDA, ONE, R( M-K+1, N-M+1 ), $ LDA ) * * Compute norm( R - A*Q' ) / ( N * norm(A) * EPS ) . * ANORM = SLANGE( '1', K, N, A( M-K+1, 1 ), LDA, RWORK ) RESID = SLANGE( '1', K, M, R( M-K+1, N-M+1 ), 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, R, LDA ) CALL SSYRK( 'Upper', 'No transpose', M, N, -ONE, Q, LDA, ONE, R, $ LDA ) * * Compute norm( I - Q*Q' ) / ( N * EPS ) . * RESID = SLANSY( '1', 'Upper', M, R, LDA, RWORK ) * RESULT( 2 ) = ( RESID / REAL( MAX( 1, N ) ) ) / EPS * RETURN * * End of SRQT02 * END