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