hypre/sstruct_ls/hypre_bsearch.c

125 lines
3.2 KiB
C

/*BHEADER**********************************************************************
* Copyright (c) 2007, Lawrence Livermore National Security, LLC.
* Produced at the Lawrence Livermore National Laboratory.
* Written by the HYPRE team. UCRL-CODE-222953.
* All rights reserved.
*
* This file is part of HYPRE (see http://www.llnl.gov/CASC/hypre/).
* Please see the COPYRIGHT_and_LICENSE file for the copyright notice,
* disclaimer, contact information and the GNU Lesser General Public License.
*
* HYPRE is free software; you can redistribute it and/or modify it under the
* terms of the GNU General Public License (as published by the Free Software
* Foundation) version 2.1 dated February 1999.
*
* HYPRE is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the IMPLIED WARRANTY OF MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the terms and conditions of the GNU General
* Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Revision$
***********************************************************************EHEADER*/
/*--------------------------------------------------------------------------
* hypre_LowerBinarySearch
* integers such that
* list[m-1] < value <= list[m].
* The routine returns location m or -1.
*--------------------------------------------------------------------------*/
int hypre_LowerBinarySearch(int *list, int value, int list_length)
{
int low, high, m;
int not_found = 1;
/* special case, list is size zero. */
if (list_length < 1)
{
return -1;
}
/* special case, list[0] >= value */
if (list[0] >= value)
{
return 0;
}
low = 0;
high= list_length-1;
while (not_found && low <= high)
{
m = (low + high) / 2;
if (m < 1)
{
m= 1;
}
if (list[m-1] < value && list[m] < value)
{
low= m + 1;
}
else if (value <= list[m-1] && value <= list[m])
{
high= m - 1;
}
else
{
not_found = 0;
return m;
}
}
return -1;
}
/*--------------------------------------------------------------------------
* hypre_UpperBinarySearch
* integers such that
* list[m] <= value < list[m+1].
* The routine returns location m or -1.
*--------------------------------------------------------------------------*/
int hypre_UpperBinarySearch(int *list, int value, int list_length)
{
int low, high, m;
int not_found = 1;
/* special case, list is size zero. */
if (list_length < 1)
{
return -1;
}
/* special case, list[list_length-1] >= value */
if (list[list_length-1] <= value)
{
return (list_length-1);
}
low = 0;
high= list_length-1;
while (not_found && low <= high)
{
m = (low + high) / 2;
if (list[m] <= value && list[m+1] <= value)
{
low= m + 1;
}
else if (value < list[m] && value < list[m+1])
{
high= m - 1;
}
else
{
not_found = 0;
return m;
}
}
return -1;
}