| *> \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 | |
| * | |
| ************************************************************************ | |