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authorGravatar Gael Guennebaud <g.gael@free.fr>2013-06-12 10:12:50 +0200
committerGravatar Gael Guennebaud <g.gael@free.fr>2013-06-12 10:12:50 +0200
commit827843bbbdb5a27019d7d679f371a3a69053c762 (patch)
tree21fb96e9f4d721dac0e2248ce93b07a86d090ad8 /lapack/dlamch.f
parent76f48205603ba1ea89022dff9537383171d69d53 (diff)
Complete the lapack interface to make it complete enough for suitesparse QR.
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+*> \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
+*
+************************************************************************