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/* Ergo, version 3.8.2, a program for linear scaling electronic structure
* calculations.
* Copyright (C) 2023 Elias Rudberg, Emanuel H. Rubensson, Pawel Salek,
* and Anastasia Kruchinina.
*
* This program 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, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Primary academic reference:
* Ergo: An open-source program for linear-scaling electronic structure
* calculations,
* Elias Rudberg, Emanuel H. Rubensson, Pawel Salek, and Anastasia
* Kruchinina,
* SoftwareX 7, 107 (2018),
* <http://dx.doi.org/10.1016/j.softx.2018.03.005>
*
* For further information about Ergo, see <http://www.ergoscf.org>.
*/
/** @file sort.h
\brief A quicksort implementation.
*/
#ifndef MAT_SORT
#define MAT_SORT
namespace mat {
#if 1
template<class Treal>
void quicksort(const Treal* value, int* index, int low, int high)
{
if(high >= low)
{
int i = low;
int j = high;
int tmp;
Treal pivot = value[index[(low + high) / 2]]; /* Introduce the pivot */
do { /* Permute elements so that all */
while (value[index[i]] < pivot) i++; /* elements end up in one of */
while (value[index[j]] > pivot) j--; /* two groups, one where the */
if (i <= j) { /* elements have a value in value */
tmp = index[i]; /* smaller than the pivot and */
index[i] = index[j]; /* one group with a value larger*/
index[j] = tmp; /* than the pivot */
i++;
j--;
}
} while (i <= j);
if(low < j) quicksort(value, index, low, j); /* Sort the two groups */
if(i < high) quicksort(value, index, i, high);
}
}
#else
template<typename Treal, typename Tfun>
void quicksort(Tfun const & fun, int* index, int low, int high)
throw(std::exception){
int i = low;
int j = high;
int tmp;
Treal pivot = fun.value(index[(low + high) / 2]); /* Introduce pivot */
do { /* Permute elements so that all */
while (fun.value(index[i]) < pivot) i++;/* elements end up in one of*/
while (fun.value(index[j]) > pivot) j--;/* two groups, one where the*/
if (i <= j) { /* elements have a value in value */
tmp = index[i]; /* smaller than the pivot and */
index[i] = index[j]; /* one group with a value larger*/
index[j] = tmp; /* than the pivot */
i++;
j--;
}
} while (i <= j);
/* Sort the two groups */
if(low < j) quicksort<Treal>(fun, index, low, j);
if(i < high) quicksort<Treal>(fun, index, i, high);
}
template<class Treal>
void quicksort(const Treal* value, int* index, int low, int high) {
int i = low;
int j = high;
int tmp;
Treal pivot = value[index[(low + high) / 2]]; /* Introduce the pivot */
do { /* Permute elements so that all */
while (value[index[i]] < pivot) i++; /* elements end up in one of */
while (value[index[j]] > pivot) j--; /* two groups, one where the */
if (i <= j) { /* elements have a value in value */
tmp = index[i]; /* smaller than the pivot and */
index[i] = index[j]; /* one group with a value larger*/
index[j] = tmp; /* than the pivot */
i++;
j--;
}
} while (i <= j);
if(low < j) quicksort(value, index, low, j); /* Sort the two groups */
if(i < high) quicksort(value, index, i, high);
}
#endif
} /* end namespace mat */
#endif
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