root / src / pauxil / HPL_pdlamch.c @ 1
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/*
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* -- High Performance Computing Linpack Benchmark (HPL)
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* HPL - 2.0 - September 10, 2008
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* Antoine P. Petitet
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* University of Tennessee, Knoxville
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* Innovative Computing Laboratory
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* (C) Copyright 2000-2008 All Rights Reserved
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*
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* -- Copyright notice and Licensing terms:
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions, and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgement:
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* This product includes software developed at the University of
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* Tennessee, Knoxville, Innovative Computing Laboratory.
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*
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* 4. The name of the University, the name of the Laboratory, or the
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* names of its contributors may not be used to endorse or promote
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* products derived from this software without specific written
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* permission.
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*
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* -- Disclaimer:
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY
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* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* ---------------------------------------------------------------------
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*/
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/*
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* Include files
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*/
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#include "hpl.h" |
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#ifdef STDC_HEADERS
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double HPL_pdlamch
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( |
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MPI_Comm COMM, |
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const HPL_T_MACH CMACH
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) |
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#else
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double HPL_pdlamch
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( COMM, CMACH ) |
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MPI_Comm COMM; |
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const HPL_T_MACH CMACH;
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#endif
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{
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/*
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* Purpose
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* =======
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*
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* HPL_pdlamch determines machine-specific arithmetic constants such as
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* the relative machine precision (eps), the safe minimum(sfmin) such that
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* 1/sfmin does not overflow, the base of the machine (base), the precision
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* (prec), the number of (base) digits in the mantissa (t), whether
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* rounding occurs in addition (rnd = 1.0 and 0.0 otherwise), the minimum
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* exponent before (gradual) underflow (emin), the underflow threshold
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* (rmin)- base**(emin-1), the largest exponent before overflow (emax), the
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* overflow threshold (rmax) - (base**emax)*(1-eps).
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*
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* Arguments
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* =========
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*
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* COMM (global/local input) MPI_Comm
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* The MPI communicator identifying the process collection.
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*
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* CMACH (global input) const HPL_T_MACH
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* Specifies the value to be returned by HPL_pdlamch
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* = HPL_MACH_EPS, HPL_pdlamch := eps (default)
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* = HPL_MACH_SFMIN, HPL_pdlamch := sfmin
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* = HPL_MACH_BASE, HPL_pdlamch := base
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* = HPL_MACH_PREC, HPL_pdlamch := eps*base
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* = HPL_MACH_MLEN, HPL_pdlamch := t
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* = HPL_MACH_RND, HPL_pdlamch := rnd
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* = HPL_MACH_EMIN, HPL_pdlamch := emin
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* = HPL_MACH_RMIN, HPL_pdlamch := rmin
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* = HPL_MACH_EMAX, HPL_pdlamch := emax
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* = HPL_MACH_RMAX, HPL_pdlamch := rmax
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*
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* where
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*
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* eps = relative machine precision,
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* sfmin = safe minimum,
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* base = base of the machine,
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* prec = eps*base,
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* t = number of digits in the mantissa,
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* rnd = 1.0 if rounding occurs in addition,
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* emin = minimum exponent before underflow,
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* rmin = underflow threshold,
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* emax = largest exponent before overflow,
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* rmax = overflow threshold.
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*
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* ---------------------------------------------------------------------
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*/
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/*
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* .. Local Variables ..
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*/
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double param;
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/* ..
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* .. Executable Statements ..
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*/
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param = HPL_dlamch( CMACH ); |
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switch( CMACH )
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{
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case HPL_MACH_EPS :
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case HPL_MACH_SFMIN :
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case HPL_MACH_EMIN :
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case HPL_MACH_RMIN :
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(void) HPL_all_reduce( (void *)(¶m), 1, HPL_DOUBLE, |
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HPL_max, COMM ); |
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break;
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case HPL_MACH_EMAX :
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case HPL_MACH_RMAX :
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(void) HPL_all_reduce( (void *)(¶m), 1, HPL_DOUBLE, |
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HPL_min, COMM ); |
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break;
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default :
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break;
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} |
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return( param );
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/*
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* End of HPL_pdlamch
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*/
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} |