*> \brief \b DGET10 * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE DGET10( M, N, A, LDA, B, LDB, WORK, RESULT ) * * .. Scalar Arguments .. * INTEGER LDA, LDB, M, N * DOUBLE PRECISION RESULT * .. * .. Array Arguments .. * DOUBLE PRECISION A( LDA, * ), B( LDB, * ), WORK( * ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DGET10 compares two matrices A and B and computes the ratio *> RESULT = norm( A - B ) / ( norm(A) * M * EPS ) *> \endverbatim * * Arguments: * ========== * *> \param[in] M *> \verbatim *> M is INTEGER *> The number of rows of the matrices A and B. *> \endverbatim *> *> \param[in] N *> \verbatim *> N is INTEGER *> The number of columns of the matrices A and B. *> \endverbatim *> *> \param[in] A *> \verbatim *> A is DOUBLE PRECISION array, dimension (LDA,N) *> The m by n matrix A. *> \endverbatim *> *> \param[in] LDA *> \verbatim *> LDA is INTEGER *> The leading dimension of the array A. LDA >= max(1,M). *> \endverbatim *> *> \param[in] B *> \verbatim *> B is DOUBLE PRECISION array, dimension (LDB,N) *> The m by n matrix B. *> \endverbatim *> *> \param[in] LDB *> \verbatim *> LDB is INTEGER *> The leading dimension of the array B. LDB >= max(1,M). *> \endverbatim *> *> \param[out] WORK *> \verbatim *> WORK is DOUBLE PRECISION array, dimension (M) *> \endverbatim *> *> \param[out] RESULT *> \verbatim *> RESULT is DOUBLE PRECISION *> RESULT = norm( A - B ) / ( norm(A) * M * EPS ) *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup double_eig * * ===================================================================== SUBROUTINE DGET10( M, N, A, LDA, B, LDB, WORK, 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 LDA, LDB, M, N DOUBLE PRECISION RESULT * .. * .. Array Arguments .. DOUBLE PRECISION A( LDA, * ), B( LDB, * ), WORK( * ) * .. * * ===================================================================== * * .. Parameters .. DOUBLE PRECISION ONE, ZERO PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) * .. * .. Local Scalars .. INTEGER J DOUBLE PRECISION ANORM, EPS, UNFL, WNORM * .. * .. External Functions .. DOUBLE PRECISION DASUM, DLAMCH, DLANGE EXTERNAL DASUM, DLAMCH, DLANGE * .. * .. External Subroutines .. EXTERNAL DAXPY, DCOPY * .. * .. Intrinsic Functions .. INTRINSIC DBLE, MAX, MIN * .. * .. Executable Statements .. * * Quick return if possible * IF( M.LE.0 .OR. N.LE.0 ) THEN RESULT = ZERO RETURN END IF * UNFL = DLAMCH( 'Safe minimum' ) EPS = DLAMCH( 'Precision' ) * WNORM = ZERO DO 10 J = 1, N CALL DCOPY( M, A( 1, J ), 1, WORK, 1 ) CALL DAXPY( M, -ONE, B( 1, J ), 1, WORK, 1 ) WNORM = MAX( WNORM, DASUM( N, WORK, 1 ) ) 10 CONTINUE * ANORM = MAX( DLANGE( '1', M, N, A, LDA, WORK ), UNFL ) * IF( ANORM.GT.WNORM ) THEN RESULT = ( WNORM / ANORM ) / ( M*EPS ) ELSE IF( ANORM.LT.ONE ) THEN RESULT = ( MIN( WNORM, M*ANORM ) / ANORM ) / ( M*EPS ) ELSE RESULT = MIN( WNORM / ANORM, DBLE( M ) ) / ( M*EPS ) END IF END IF * RETURN * * End of DGET10 * END