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muSpectre/src/common/ccoord_operations.hh
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ccoord_operations.hh
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/**
* @file ccoord_operations.hh
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 29 Sep 2017
*
* @brief common operations on pixel addressing
*
* Copyright © 2017 Till Junge
*
* µSpectre 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, or (at
* your option) any later version.
*
* µSpectre 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 GNU Emacs; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <functional>
#include <numeric>
#include <vector>
#include <utility>
#include <Eigen/Dense>
#include "common/common.hh"
#include "common/iterators.hh"
#ifndef CCOORD_OPERATIONS_H
#define CCOORD_OPERATIONS_H
namespace muSpectre {
namespace CcoordOps {
namespace internal {
//! simple helper returning the first argument and ignoring the second
template <typename T>
constexpr T ret(T val, size_t /*dummy*/) {return val;}
//! helper to build cubes
template <Dim_t Dim, typename T, size_t... I>
constexpr std::array<T, Dim> cube_fun(T val, std::index_sequence<I...>) {
return std::array<T, Dim>{ret(val, I)...};
}
//! computes hermitian size according to FFTW
template <Dim_t Dim, size_t... I>
constexpr Ccoord_t<Dim> herm(const Ccoord_t<Dim> & full_sizes,
std::index_sequence<I...>) {
return Ccoord_t<Dim>{full_sizes[I]..., full_sizes.back()/2+1};
}
//! compute the stride in a direction of a row-major grid
template <Dim_t Dim>
constexpr Dim_t stride(const Ccoord_t<Dim> & sizes,
const size_t index) {
static_assert(Dim > 0, "only for positive numbers of dimensions");
auto const diff{Dim - 1 - Dim_t(index)};
Dim_t ret_val{1};
for (Dim_t i{0}; i < diff; ++i) {
ret_val *= sizes[Dim-1-i];
}
return ret_val;
}
//! get all strides from a row-major grid (helper function)
template <Dim_t Dim, size_t... I>
constexpr Ccoord_t<Dim> compute_strides(const Ccoord_t<Dim> & sizes,
std::index_sequence<I...>) {
return Ccoord_t<Dim>{stride<Dim>(sizes, I)...};
}
} // internal
//----------------------------------------------------------------------------//
//! returns a grid of equal resolutions in each direction
template <size_t dim, typename T>
constexpr std::array<T, dim> get_cube(T size) {
return internal::cube_fun<dim>(size, std::make_index_sequence<dim>{});
}
/* ---------------------------------------------------------------------- */
//! returns the hermition grid to correcsponding to a full grid
template <size_t dim>
constexpr Ccoord_t<dim> get_hermitian_sizes(Ccoord_t<dim> full_sizes) {
return internal::herm<dim>(full_sizes, std::make_index_sequence<dim-1>{});
}
/* ---------------------------------------------------------------------- */
//! return physical vector of a cell of cubic pixels
template <size_t dim>
Eigen::Matrix<Real, dim, 1> get_vector(const Ccoord_t<dim> & ccoord, Real pix_size = 1.) {
Eigen::Matrix<Real, dim, 1> retval;
for (size_t i = 0; i < dim; ++i) {
retval[i] = pix_size * ccoord[i];
}
return retval;
}
/* ---------------------------------------------------------------------- */
//! return physical vector of a cell of general pixels
template <size_t dim, typename T>
Eigen::Matrix<T, dim, 1> get_vector(const Ccoord_t<dim> & ccoord,
Eigen::Matrix<T, Dim_t(dim), 1> pix_size) {
Eigen::Matrix<T, dim, 1> retval = pix_size;
for (size_t i = 0; i < dim; ++i) {
retval[i] *= ccoord[i];
}
return retval;
}
/* ---------------------------------------------------------------------- */
//! return physical vector of a cell of general pixels
template <size_t dim, typename T>
Eigen::Matrix<T, dim, 1> get_vector(const Ccoord_t<dim> & ccoord,
const std::array<T, dim>& pix_size) {
Eigen::Matrix<T, dim, 1> retval{};
for (size_t i = 0; i < dim; ++i) {
retval[i] = pix_size[i]*ccoord[i];
}
return retval;
}
/* ---------------------------------------------------------------------- */
//! get all strides from a row-major grid
template <size_t dim>
constexpr Ccoord_t<dim> get_default_strides(const Ccoord_t<dim> & sizes) {
return internal::compute_strides<dim>(sizes,
std::make_index_sequence<dim>{});
}
//----------------------------------------------------------------------------//
//! get the i-th pixel in a grid of size sizes
template <size_t dim>
constexpr Ccoord_t<dim> get_ccoord(const Ccoord_t<dim> & sizes, Dim_t index) {
Ccoord_t<dim> retval{{0}};
Dim_t factor{1};
for (Dim_t i = dim-1; i >=0; --i) {
retval[i] = index/factor%sizes[i];
if (i != 0 ) {
factor *= sizes[i];
}
}
return retval;
}
//----------------------------------------------------------------------------//
//! get the linear index of a pixel in a given grid
template <size_t dim>
constexpr Dim_t get_index(const Ccoord_t<dim> & sizes,
const Ccoord_t<dim> & ccoord) {
Dim_t retval{0};
Dim_t factor{1};
for (Dim_t i = dim-1; i >=0; --i) {
retval += ccoord[i]*factor;
if (i != 0) {
factor *= sizes[i];
}
}
return retval;
}
//----------------------------------------------------------------------------//
//! get the linear index of a pixel given a set of strides
template <size_t dim>
constexpr Dim_t get_index_from_strides(const Ccoord_t<dim> & strides,
const Ccoord_t<dim> & ccoord) {
Dim_t retval{0};
for (const auto & tup: akantu::zip(strides, ccoord)) {
const auto & stride = std::get<0>(tup);
const auto & ccord_ = std::get<1>(tup);
retval += stride * ccord_;
}
return retval;
}
//----------------------------------------------------------------------------//
//! get the number of pixels in a grid
template <size_t dim>
constexpr size_t get_size(const Ccoord_t<dim>& sizes) {
Dim_t retval{1};
for (size_t i = 0; i < dim; ++i) {
retval *= sizes[i];
}
return retval;
}
//----------------------------------------------------------------------------//
//! get the number of pixels in a grid given its strides
template <size_t dim>
constexpr size_t get_size_from_strides(const Ccoord_t<dim>& sizes,
const Ccoord_t<dim>& strides) {
return sizes[0]*strides[0];
}
/* ---------------------------------------------------------------------- */
/**
* centralises iterating over square (or cubic) discretisation grids
*/
template <size_t dim>
class Pixels {
public:
//! constructor
Pixels(const Ccoord_t<dim> & sizes=Ccoord_t<dim>{}):sizes(sizes){};
//! copy constructor
Pixels(const Pixels & other) = default;
//! assignment operator
Pixels & operator=(const Pixels & other) = default;
virtual ~Pixels() = default;
/**
* iterators over `Pixels` dereferences to cell coordinates
*/
class iterator
{
public:
using value_type = Ccoord_t<dim>; //!< stl conformance
using const_value_type = const value_type; //!< stl conformance
using pointer = value_type*; //!< stl conformance
using difference_type = std::ptrdiff_t; //!< stl conformance
using iterator_category = std::forward_iterator_tag;//!<stl conformance
using reference = value_type; //!< stl conformance
//! constructor
iterator(const Pixels & pixels, bool begin=true);
virtual ~iterator() = default;
//! dereferencing
inline value_type operator*() const;
//! pre-increment
inline iterator & operator++();
//! inequality
inline bool operator!=(const iterator & other) const;
//! equality
inline bool operator==(const iterator & other) const;
protected:
const Pixels& pixels; //!< ref to pixels in cell
size_t index; //!< index of currect pointed-to pixel
};
//! stl conformance
inline iterator begin() const {return iterator(*this);}
//! stl conformance
inline iterator end() const {return iterator(*this, false);}
//! stl conformance
inline size_t size() const {return get_size(this->sizes);}
protected:
Ccoord_t<dim> sizes; //!< resolutions of cell
};
/* ---------------------------------------------------------------------- */
template <size_t dim>
Pixels<dim>::iterator::iterator(const Pixels & pixels, bool begin)
:pixels{pixels}, index{begin? 0: get_size(pixels.sizes)}
{}
/* ---------------------------------------------------------------------- */
template <size_t dim>
typename Pixels<dim>::iterator::value_type
Pixels<dim>::iterator::operator*() const {
return get_ccoord(pixels.sizes, this->index);
}
/* ---------------------------------------------------------------------- */
template <size_t dim>
bool
Pixels<dim>::iterator::operator!=(const iterator &other) const {
return (this->index != other.index) || (&this->pixels != &other.pixels);
}
/* ---------------------------------------------------------------------- */
template <size_t dim>
bool
Pixels<dim>::iterator::operator==(const iterator &other) const {
return !(*this!= other);
}
/* ---------------------------------------------------------------------- */
template <size_t dim>
typename Pixels<dim>::iterator&
Pixels<dim>::iterator::operator++() {
++this->index;
return *this;
}
} // CcoordOps
} // muSpectre
#endif /* CCOORD_OPERATIONS_H */
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