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HPL_pdlamch(3)		     HPL Library Functions		HPL_pdlamch(3)

NAME
       HPL_pdlamch - determines	machine-specific arithmetic constants.

SYNOPSIS
       #include	"hpl.h"

       double HPL_pdlamch( MPI_Comm COMM, const	HPL_T_MACH CMACH );

DESCRIPTION
       HPL_pdlamch  determines	 machine-specific  arithmetic  constants  such
       as the relative machine precision (eps),	 the safe minimum(sfmin)  such
       that  1/sfmin  does  not	 overflow, the base of the machine (base), the
       precision (prec),  the  number  of  (base)   digits  in	the   mantissa
       (t),   whether  rounding	 occurs	 in addition (rnd = 1.0	and 0.0	other-
       wise),  the  minimum exponent before  (gradual)	underflow (emin),  the
       underflow   threshold  (rmin)- base**(emin-1), the largest exponent be-
       fore   overflow	 (emax),   the	 overflow    threshold	  (rmax)     -
       (base**emax)*(1-eps).

ARGUMENTS
       COMM    (global/local input)    MPI_Comm
	       The MPI communicator identifying	the process collection.

       CMACH   (global input)	       const HPL_T_MACH
	       Specifies the value to be returned by HPL_pdlamch
		  = HPL_MACH_EPS,   HPL_pdlamch	:= eps (default)
		  = HPL_MACH_SFMIN, HPL_pdlamch	:= sfmin
		  = HPL_MACH_BASE,  HPL_pdlamch	:= base
		  = HPL_MACH_PREC,  HPL_pdlamch	:= eps*base
		  = HPL_MACH_MLEN,  HPL_pdlamch	:= t
		  = HPL_MACH_RND,   HPL_pdlamch	:= rnd
		  = HPL_MACH_EMIN,  HPL_pdlamch	:= emin
		  = HPL_MACH_RMIN,  HPL_pdlamch	:= rmin
		  = HPL_MACH_EMAX,  HPL_pdlamch	:= emax
		  = HPL_MACH_RMAX,  HPL_pdlamch	:= rmax

	       where

		  eps	= relative machine precision,
		  sfmin	= safe minimum,
		  base	= base of the machine,
		  prec	= eps*base,
		  t	= number of digits in the mantissa,
		  rnd	= 1.0 if rounding occurs in addition,
		  emin	= minimum exponent before underflow,
		  rmin	= underflow threshold,
		  emax	= largest exponent before overflow,
		  rmax	= overflow threshold.

HPL 2.1			       October 26, 2012			HPL_pdlamch(3)

NAME | SYNOPSIS | DESCRIPTION | ARGUMENTS

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