Scalar.hh

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/* Copyright (C) 2022, 2023 PISM Authors
 *
 * This file is part of PISM.
 *
 * PISM 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.
 *
 * PISM 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 PISM; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
#ifndef PISM_ARRAY_SCALAR_H
#define PISM_ARRAY_SCALAR_H
 
#include <cmath>                // floor()
 
#include "pism/util/array/Array2D.hh"
 
namespace pism {
namespace array {
 
/** A class for storing and accessing scalar 2D fields. */
class Scalar : public Array2D<double> {
public:
  Scalar(std::shared_ptr<const Grid> grid, const std::string &name);
 
  std::shared_ptr<Scalar> duplicate() const;
 
  inline int as_int(int i, int j) const;
 
protected:
  inline stencils::Star<int> star_int(int i, int j) const;
  inline stencils::Box<int> box_int(int i, int j) const;
  Scalar(std::shared_ptr<const Grid> grid, const std::string &name, int width);
};
 
inline int Scalar::as_int(int i, int j) const {
  const double &value = (*this)(i, j);
  return static_cast<int>(floor(value + 0.5));
}
 
/*!
 * Scalar 2D array supporting width=1 stencil computations
 */
class Scalar1 : public Scalar {
public:
  Scalar1(std::shared_ptr<const Grid> grid, const std::string &name);
  using Array2D<double>::star;
  using Array2D<double>::box;
  using Scalar::star_int;
  using Scalar::box_int;
protected:
  Scalar1(std::shared_ptr<const Grid> grid, const std::string &name, int width);
};
 
/*!
 * Scalar 2D array supporting width=2 stencil computations
 */
class Scalar2 : public Scalar1 {
public:
  Scalar2(std::shared_ptr<const Grid> grid, const std::string &name);
};
 
inline stencils::Star<int> Scalar::star_int(int i, int j) const {
  stencils::Star<int> result;
 
  result.c = as_int(i,j);
  result.e = as_int(i+1,j);
  result.w = as_int(i-1,j);
  result.n = as_int(i,j+1);
  result.s = as_int(i,j-1);
 
  return result;
}
 
inline stencils::Box<int> Scalar::box_int(int i, int j) const {
  const int
      E = i + 1,
      W = i - 1,
      N = j + 1,
      S = j - 1;
 
  return {as_int(i, j), as_int(i, N), as_int(W, N), as_int(W, j), as_int(W, S),
          as_int(i, S), as_int(E, S), as_int(E, j), as_int(E, N)};
}
 
// Finite-difference shortcuts. They may be slower than hard-coding FD approximations of x
// and y derivatives. Use with care.
double diff_x(const array::Scalar &array, int i, int j);
double diff_y(const array::Scalar &array, int i, int j);
 
// These take grid periodicity into account and use one-sided differences at domain edges.
double diff_x_p(const array::Scalar &array, int i, int j);
double diff_y_p(const array::Scalar &array, int i, int j);
 
double sum(const array::Scalar &input);
double min(const array::Scalar &input);
double max(const array::Scalar &input);
double absmax(const array::Scalar &input);
 
void apply_mask(const array::Scalar &M, double fill, array::Scalar &result);
 
} // end of namespace array
 
} // end of namespace pism
 
#endif /* PISM_ARRAY_SCALAR_H */