gravity.c

/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2017 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/>.
 *
 ******************************************************************************/

/* Config parameters. */
#include "../config.h"

/* Some standard headers. */
#include <stdio.h>
#include <unistd.h>

/* This object's header. */
#include "gravity.h"

/* Local headers. */
#include "active.h"
#include "error.h"
#include "version.h"

/**
 * @brief Checks whether the file containing the exact accelerations for
 * the current choice of parameters already exists.
 *
 * @param e The #engine.
 */
int gravity_exact_force_file_exits(const struct engine *e) {

#ifdef SWIFT_GRAVITY_FORCE_CHECKS

  /* File name */
  char file_name[100];
  sprintf(file_name, "gravity_checks_exact_step%d.dat", e->step);

  /* Does the file exist ? */
  if (access(file_name, R_OK | W_OK) == 0) {

    /* Let's check whether the header matches the parameters of this run */
    FILE *file = fopen(file_name, "r");
    if (!file) error("Problem reading gravity_check file");

    char line[100];
    char dummy1[10], dummy2[10];
    double epsilon, newton_G;
    int N;
    /* Reads file header */
    if (fgets(line, 100, file) != line) error("Problem reading title");
    if (fgets(line, 100, file) != line) error("Problem reading G");
    sscanf(line, "%s %s %le", dummy1, dummy2, &newton_G);
    if (fgets(line, 100, file) != line) error("Problem reading N");
    sscanf(line, "%s %s %d", dummy1, dummy2, &N);
    if (fgets(line, 100, file) != line) error("Problem reading epsilon");
    sscanf(line, "%s %s %le", dummy1, dummy2, &epsilon);
    fclose(file);

    /* Check whether it matches the current parameters */