87 lines
2.2 KiB
Fortran
87 lines
2.2 KiB
Fortran
*> \brief \b DROUNDUP_LWORK
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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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* DOUBLE PRECISION FUNCTION DROUNDUP_LWORK( LWORK )
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*
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* .. Scalar Arguments ..
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* INTEGER LWORK
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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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*> DROUNDUP_LWORK deals with a subtle bug with returning LWORK as a Float.
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*> This routine guarantees it is rounded up instead of down by
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*> multiplying LWORK by 1+eps when it is necessary, where eps is the relative machine precision.
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*> E.g.,
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*>
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*> float( 9007199254740993 ) == 9007199254740992
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*> float( 9007199254740993 ) * (1.+eps) == 9007199254740994
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*>
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*> \return DROUNDUP_LWORK
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*> \verbatim
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*> DROUNDUP_LWORK >= LWORK.
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*> DROUNDUP_LWORK is guaranteed to have zero decimal part.
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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] LWORK Workspace size.
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*
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* Authors:
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* ========
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*
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*> \author Weslley Pereira, University of Colorado Denver, USA
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*
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*> \ingroup auxOTHERauxiliary
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*
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*> \par Further Details:
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* =====================
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*>
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*> \verbatim
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*> This routine was inspired in the method `magma_zmake_lwork` from MAGMA.
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*> \see https://bitbucket.org/icl/magma/src/master/control/magma_zauxiliary.cpp
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*> \endverbatim
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*
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* =====================================================================
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DOUBLE PRECISION FUNCTION DROUNDUP_LWORK( LWORK )
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*
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* -- LAPACK auxiliary 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 LWORK
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* ..
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*
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* =====================================================================
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC EPSILON, DBLE, INT
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* ..
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* .. Executable Statements ..
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* ..
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DROUNDUP_LWORK = DBLE( LWORK )
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*
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IF( INT( DROUNDUP_LWORK ) .LT. LWORK ) THEN
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* Force round up of LWORK
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DROUNDUP_LWORK = DROUNDUP_LWORK * ( 1.0D+0 + EPSILON(0.0D+0) )
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ENDIF
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*
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RETURN
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*
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* End of DROUNDUP_LWORK
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*
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END
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