Quelle dlamch.f Sprache: Fortran

*> \brief \b DLAMCH
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*  Definition:
*  ===========
*
*      DOUBLE PRECISION FUNCTION DLAMCH( CMACH )
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DLAMCH determines double precision machine parameters.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] CMACH
*> \verbatim
*>          Specifies the value to be returned by DLAMCH:
*>          = 'E' or 'e',   DLAMCH := eps
*>          = 'S' or 's , DLAMCH := sfmin
*>          = 'B' or 'b',   DLAMCH := base
*>          = 'P' or 'p',   DLAMCH := eps*base
*>          = 'N' or 'n',   DLAMCH := t
*>          = 'R' or 'r',   DLAMCH := rnd
*>          = 'M' or 'm',   DLAMCH := emin
*>          = 'U' or 'u',   DLAMCH := rmin
*>          = 'L' or 'l',   DLAMCH := emax
*>          = 'O' or 'o',   DLAMCH := rmax
*>          where
*>          eps   = relative machine precision
*>          sfmin = safe minimum, such that 1/sfmin does not overflow
*>          base  = base of the machine
*>          prec  = eps*base
*>          t     = number of (base) digits in the mantissa
*>          rnd   = 1.0 when rounding occurs in addition, 0.0 otherwise
*>          emin  = minimum exponent before (gradual) underflow
*>          rmin  = underflow threshold - base**(emin-1)
*>          emax  = largest exponent before overflow
*>          rmax  = overflow threshold  - (base**emax)*(1-eps)
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2011
*
*> \ingroup auxOTHERauxiliary
*
*  =====================================================================
      DOUBLE PRECISION FUNCTION DLAMCH( CMACH )
*
*  -- LAPACK auxiliary routine (version 3.4.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     November 2011
*
*     .. Scalar Arguments ..
      CHARACTER          CMACH
*     ..
*
* =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      DOUBLE PRECISION   RND, EPS, SFMIN, SMALL, RMACH
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          DIGITS, EPSILON, HUGE, MAXEXPONENT,
     $                   MINEXPONENT, RADIX, TINY
*     ..
*     .. Executable Statements ..
*
*
*     Assume rounding, not chopping. Always.
*
      RND = ONE
*
      IF( ONE.EQ.RND ) THEN
         EPS = EPSILON(ZERO) * 0.5
      ELSE
         EPS = EPSILON(ZERO)
      END IF
*
      IF( LSAME( CMACH, 'E' ) ) THEN
         RMACH = EPS
      ELSE IF( LSAME( CMACH, 'S' ) ) THEN
         SFMIN = TINY(ZERO)
         SMALL = ONE / HUGE(ZERO)
         IF( SMALL.GE.SFMIN ) THEN
*
*           Use SMALL plus a bit, to avoid the possibility of rounding
*           causing overflow when computing  1/sfmin.
*
            SFMIN = SMALL*( ONE+EPS )
         END IF
         RMACH = SFMIN
      ELSE IF( LSAME( CMACH, 'B' ) ) THEN
         RMACH = RADIX(ZERO)
      ELSE IF( LSAME( CMACH, 'P' ) ) THEN
         RMACH = EPS * RADIX(ZERO)
      ELSE IF( LSAME( CMACH, 'N' ) ) THEN
         RMACH = DIGITS(ZERO)
      ELSE IF( LSAME( CMACH, 'R' ) ) THEN
         RMACH = RND
      ELSE IF( LSAME( CMACH, 'M' ) ) THEN
         RMACH = MINEXPONENT(ZERO)
      ELSE IF( LSAME( CMACH, 'U' ) ) THEN
         RMACH = tiny(zero)
      ELSE IF( LSAME( CMACH, 'L' ) ) THEN
         RMACH = MAXEXPONENT(ZERO)
      ELSE IF( LSAME( CMACH, 'O' ) ) THEN
         RMACH = HUGE(ZERO)
      ELSE
         RMACH = ZERO
      END IF
*
      DLAMCH = RMACH
      RETURN
*
*     End of DLAMCH
*
      END
************************************************************************
*> \brief \b DLAMC3
*> \details
*> \b Purpose:
*> \verbatim
*> DLAMC3  is intended to force  A  and  B  to be stored prior to doing
*> the addition of  A  and  B ,  for use in situations where optimizers
*> might hold one of these in a register.
*> \endverbatim
*> \author LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..
*> \date November 2011
*> \ingroup auxOTHERauxiliary
*>
*> \param[in] A
*> \verbatim
*>          A is a DOUBLE PRECISION
*> \endverbatim
*>
*> \param[in] B
*> \verbatim
*>          B is a DOUBLE PRECISION
*>          The values A and B.
*> \endverbatim
*>
      DOUBLE PRECISION FUNCTION DLAMC3( A, B )
*
*  -- LAPACK auxiliary routine (version 3.4.0) --
*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
*     November 2010
*
*     .. Scalar Arguments ..
      DOUBLE PRECISION   A, B
*     ..
* =====================================================================
*
*     .. Executable Statements ..
*
      DLAMC3 = A + B
*
      RETURN
*
*     End of DLAMC3
*
      END
*
************************************************************************

quality100%

¤ Dauer der Verarbeitung: 0.2 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.