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multipole.h 4.35 KiB
/*******************************************************************************
* This file is part of SWIFT.
* Copyright (c) 2013 Pedro Gonnet (pedro.gonnet@durham.ac.uk)
* 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser 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 Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
******************************************************************************/
#ifndef SWIFT_MULTIPOLE_H
#define SWIFT_MULTIPOLE_H
/* Some standard headers. */
#include <math.h>
/* Includes. */
#include "const.h"
#include "inline.h"
#include "kernel_gravity.h"
#include "part.h"
/* Multipole struct. */
struct multipole {
/* Multipole location. */
double CoM[3];
/* Multipole mass */
float mass;
#if const_gravity_multipole_order >= 2
/* Quadrupole terms */
float I_xx, I_yy, I_zz;
float I_xy, I_xz, I_yz;
#endif
};
/* Multipole function prototypes. */
void multipole_add(struct multipole *m_sum, const struct multipole *m_term);
void multipole_init(struct multipole *m, const struct gpart *gparts,
int gcount);
void multipole_reset(struct multipole *m);
/* static void multipole_iact_mm(struct multipole *ma, struct multipole *mb, */
/* double *shift); */
/* void multipole_addpart(struct multipole *m, struct gpart *p); */
/* void multipole_addparts(struct multipole *m, struct gpart *p, int N); */
/**
* @brief Compute the pairwise interaction between two multipoles.
*
* @param ma The first #multipole.
* @param mb The second #multipole.
* @param shift The periodicity correction.
*/
__attribute__((always_inline)) INLINE static void multipole_iact_mm(
struct multipole *ma, struct multipole *mb, double *shift) {
/* float dx[3], ir, r, r2 = 0.0f, acc; */
/* int k; */
/* /\* Compute the multipole distance. *\/ */
/* for (k = 0; k < 3; k++) { */
/* dx[k] = ma->x[k] - mb->x[k] - shift[k]; */
/* r2 += dx[k] * dx[k]; */
/* } */
/* /\* Compute the normalized distance vector. *\/ */
/* ir = 1.0f / sqrtf(r2); */
/* r = r2 * ir; */
/* /\* Evaluate the gravity kernel. *\/ */
/* kernel_grav_eval(r, &acc); */
/* /\* Scale the acceleration. *\/ */
/* acc *= const_G * ir * ir * ir; */
/* /\* Compute the forces on both multipoles. *\/ */
/* #if const_gravity_multipole_order == 1 */
/* float mma = ma->coeffs[0], mmb = mb->coeffs[0]; */
/* for (k = 0; k < 3; k++) { */
/* ma->a[k] -= dx[k] * acc * mmb; */
/* mb->a[k] += dx[k] * acc * mma; */
/* } */
/* #else */
/* #error( "Multipoles of order %i not yet implemented." ,
* const_gravity_multipole_order )
*/
/* #endif */
}
/**
* @brief Compute the interaction of a multipole on a particle.
*
* @param m The #multipole.
* @param p The #gpart.
* @param shift The periodicity correction.
*/
__attribute__((always_inline)) INLINE static void multipole_iact_mp(
struct multipole *m, struct gpart *p, double *shift) {
/* float dx[3], ir, r, r2 = 0.0f, acc; */
/* int k; */
/* /\* Compute the multipole distance. *\/ */
/* for (k = 0; k < 3; k++) { */
/* dx[k] = m->x[k] - p->x[k] - shift[k]; */
/* r2 += dx[k] * dx[k]; */
/* } */
/* /\* Compute the normalized distance vector. *\/ */
/* ir = 1.0f / sqrtf(r2); */
/* r = r2 * ir; */
/* /\* Evaluate the gravity kernel. *\/ */
/* kernel_grav_eval(r, &acc); */
/* /\* Scale the acceleration. *\/ */
/* acc *= const_G * ir * ir * ir * m->coeffs[0]; */
/* /\* Compute the forces on both multipoles. *\/ */
/* #if const_gravity_multipole_order == 1 */
/* for (k = 0; k < 3; k++) p->a_grav[k] += dx[k] * acc; */
/* #else */
/* #error( "Multipoles of order %i not yet implemented." ,
* const_gravity_multipole_order )
*/
/* #endif */
}
#endif /* SWIFT_MULTIPOLE_H */