ESPResSo
Extensible Simulation Package for Research on Soft Matter Systems
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index.hpp
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/*
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* Copyright (C) 2010-2022 The ESPResSo project
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*
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* This file is part of ESPResSo.
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*
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* ESPResSo is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* ESPResSo is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <cassert>
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#include <cstddef>
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#include <iterator>
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#include <numeric>
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#include <stdexcept>
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#include "
Vector.hpp
"
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namespace
Utils
{
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enum class
MemoryOrder
{
COLUMN_MAJOR
,
ROW_MAJOR
};
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/** get the linear index from the position (@p a,@p b,@p c) in a 3D grid
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* of dimensions @p adim.
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*
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* @return The linear index
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* @param a , b , c Position in 3D space
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* @param adim Dimensions of the underlying grid
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* @param memory_order Row- or column-major
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*/
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inline
int
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get_linear_index
(
int
a,
int
b,
int
c,
const
Vector3i
&adim,
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MemoryOrder
memory_order =
MemoryOrder::COLUMN_MAJOR
) {
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assert((a >= 0) && (a < adim[0]));
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assert((b >= 0) && (b < adim[1]));
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assert((c >= 0) && (c < adim[2]));
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if
(memory_order ==
MemoryOrder::COLUMN_MAJOR
) {
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return
a + adim[0] * (b + adim[1] * c);
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}
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return
adim[1] * adim[2] * a + adim[2] * b + c;
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}
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inline
int
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get_linear_index
(
const
Vector3i
&ind,
const
Vector3i
&adim,
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MemoryOrder
memory_order =
MemoryOrder::COLUMN_MAJOR
) {
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return
get_linear_index
(ind[0], ind[1], ind[2], adim, memory_order);
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}
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/**
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* @brief Linear index into a lower triangular matrix.
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*
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* This is row-major.
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*
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* @tparam T Integral type
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* @param i row index
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* @param j column index
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* @return linear index
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*/
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template
<
class
T> T
lower_triangular
(T i, T j) {
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/* i is a valid row index */
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assert(i >= 0);
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/* j is in the lower triangle */
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assert(j >= 0 and j <= i);
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return
(i * (i + 1)) / 2 + j;
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}
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}
// namespace Utils
Vector.hpp
Vector implementation and trait types for boost qvm interoperability.
Utils::Vector
Definition
Vector.hpp:48
Utils
Definition
Variant.hpp:40
Utils::get_linear_index
int get_linear_index(int a, int b, int c, const Vector3i &adim, MemoryOrder memory_order=MemoryOrder::COLUMN_MAJOR)
get the linear index from the position (a,b,c) in a 3D grid of dimensions adim.
Definition
index.hpp:43
Utils::lower_triangular
T lower_triangular(T i, T j)
Linear index into a lower triangular matrix.
Definition
index.hpp:71
Utils::MemoryOrder
MemoryOrder
Definition
index.hpp:32
Utils::MemoryOrder::ROW_MAJOR
@ ROW_MAJOR
Utils::MemoryOrder::COLUMN_MAJOR
@ COLUMN_MAJOR
src
utils
include
utils
index.hpp
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