test125cells.c 20.7 KB
Newer Older
1
2
/*******************************************************************************
 * This file is part of SWIFT.
3
 * Copyright (C) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk).
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
 *
 * 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/>.
 *
 ******************************************************************************/

20
21
22
23
/* Config parameters. */
#include "../config.h"

/* Some standard headers. */
24
25
26
27
28
29
#include <fenv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

30
31
/* Local headers. */
#include "swift.h"
32

33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
enum velocity_field {
  velocity_zero,
  velocity_const,
  velocity_divergent,
  velocity_rotating
};

enum pressure_field { pressure_const, pressure_gradient, pressure_divergent };

void set_velocity(struct part *part, enum velocity_field vel, float size) {

  switch (vel) {
    case velocity_zero:
      part->v[0] = 0.f;
      part->v[1] = 0.f;
      part->v[2] = 0.f;
      break;
    case velocity_const:
      part->v[0] = 1.f;
      part->v[1] = 0.f;
      part->v[2] = 0.f;
      break;
    case velocity_divergent:
      part->v[0] = part->x[0] - 2.5 * size;
      part->v[1] = part->x[1] - 2.5 * size;
      part->v[2] = part->x[2] - 2.5 * size;
      break;
    case velocity_rotating:
      part->v[0] = part->x[1];
      part->v[1] = -part->x[0];
      part->v[2] = 0.f;
      break;
  }
}

float get_pressure(double x[3], enum pressure_field press, float size) {

  float r2 = 0.;
  float dx[3] = {0.f};

  switch (press) {
    case pressure_const:
      return 1.5f;
      break;
    case pressure_gradient:
      return 1.5f * x[0]; /* gradient along x */
      break;
    case pressure_divergent:
      dx[0] = x[0] - 2.5 * size;
      dx[1] = x[1] - 2.5 * size;
      dx[2] = x[2] - 2.5 * size;
      r2 = dx[0] * dx[0] + dx[1] * dx[1] + dx[2] * dx[2];
      return sqrt(r2) + 1.5f;
      break;
  }
  return 0.f;
}

void set_energy_state(struct part *part, enum pressure_field press, float size,
                      float density) {

  const float pressure = get_pressure(part->x, press, size);

#if defined(GADGET2_SPH)
  part->entropy = pressure / pow_gamma(density);
98
99
#elif defined(DEFAULT_SPH)
  part->u = pressure / (hydro_gamma_minus_one * density);
Matthieu Schaller's avatar
Matthieu Schaller committed
100
101
#elif defined(MINIMAL_SPH)
  part->u = pressure / (hydro_gamma_minus_one * density);
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
#else
  error("Need to define pressure here !");
#endif
}

struct solution_part {

  long long id;
  double x[3];
  float v[3];
  float a_hydro[3];
  float h;
  float rho;
  float div_v;
  float S;
  float u;
  float P;
  float c;
  float h_dt;
  float v_sig;
  float S_dt;
  float u_dt;
};

void get_solution(const struct cell *main_cell, struct solution_part *solution,
                  float density, enum velocity_field vel,
                  enum pressure_field press, float size) {

  for (size_t i = 0; i < main_cell->count; ++i) {

    solution[i].id = main_cell->parts[i].id;

    solution[i].x[0] = main_cell->parts[i].x[0];
    solution[i].x[1] = main_cell->parts[i].x[1];
    solution[i].x[2] = main_cell->parts[i].x[2];

    solution[i].v[0] = main_cell->parts[i].v[0];
    solution[i].v[1] = main_cell->parts[i].v[1];
    solution[i].v[2] = main_cell->parts[i].v[2];

    solution[i].h = main_cell->parts[i].h;

    solution[i].rho = density;

    solution[i].P = get_pressure(solution[i].x, press, size);
    solution[i].u = solution[i].P / (solution[i].rho * hydro_gamma_minus_one);
    solution[i].S = solution[i].P / pow_gamma(solution[i].rho);
    solution[i].c = sqrt(hydro_gamma * solution[i].P / solution[i].rho);

    if (vel == velocity_divergent)
      solution[i].div_v = 3.f;
    else
      solution[i].div_v = 0.f;

    solution[i].h_dt = solution[i].h * solution[i].div_v / 3.;

    float gradP[3] = {0.f};
    if (press == pressure_gradient) {
      gradP[0] = 1.5f;
      gradP[1] = 0.f;
      gradP[2] = 0.f;
    } else if (press == pressure_divergent) {
      float dx[3];
      dx[0] = solution[i].x[0] - 2.5 * size;
      dx[1] = solution[i].x[1] - 2.5 * size;
      dx[2] = solution[i].x[2] - 2.5 * size;
      float r = sqrt(dx[0] * dx[0] + dx[1] * dx[1] + dx[2] * dx[2]);
      if (r > 0.) {
        gradP[0] = dx[0] / r;
        gradP[1] = dx[1] / r;
        gradP[2] = dx[2] / r;
      }
    }

    solution[i].a_hydro[0] = -gradP[0] / solution[i].rho;
    solution[i].a_hydro[1] = -gradP[1] / solution[i].rho;
    solution[i].a_hydro[2] = -gradP[2] / solution[i].rho;

    solution[i].v_sig = 2.f * solution[i].c;
181
182
183

    solution[i].S_dt = 0.f;
    solution[i].u_dt = -(solution[i].P / solution[i].rho) * solution[i].div_v;
184
185
186
  }
}

187
188
189
190
191
192
193
194
195
196
197
198
void reset_particles(struct cell *c, enum velocity_field vel,
                     enum pressure_field press, float size, float density) {

  for (size_t i = 0; i < c->count; ++i) {

    struct part *p = &c->parts[i];

    set_velocity(p, vel, size);
    set_energy_state(p, press, size, density);
  }
}

199
200
/**
 * @brief Constructs a cell and all of its particle in a valid state prior to
201
 * a SPH time-step.
202
203
204
205
206
 *
 * @param n The cube root of the number of particles.
 * @param offset The position of the cell offset from (0,0,0).
 * @param size The cell size.
 * @param h The smoothing length of the particles in units of the inter-particle
207
 * separation.
208
209
 * @param density The density of the fluid.
 * @param partId The running counter of IDs.
210
211
 * @param vel The type of velocity field.
 * @param press The type of pressure field.
212
 */
213
struct cell *make_cell(size_t n, const double offset[3], double size, double h,
214
215
                       double density, long long *partId,
                       enum velocity_field vel, enum pressure_field press) {
216

217
218
219
220
221
222
  const size_t count = n * n * n;
  const double volume = size * size * size;
  struct cell *cell = malloc(sizeof(struct cell));
  bzero(cell, sizeof(struct cell));

  if (posix_memalign((void **)&cell->parts, part_align,
223
                     count * sizeof(struct part)) != 0)
224
    error("couldn't allocate particles, no. of particles: %d", (int)count);
225
226
227
  if (posix_memalign((void **)&cell->xparts, xpart_align,
                     count * sizeof(struct xpart)) != 0)
    error("couldn't allocate particles, no. of x-particles: %d", (int)count);
228
  bzero(cell->parts, count * sizeof(struct part));
229
  bzero(cell->xparts, count * sizeof(struct xpart));
230
231
232

  /* Construct the parts */
  struct part *part = cell->parts;
233
  struct xpart *xpart = cell->xparts;
234
235
236
  for (size_t x = 0; x < n; ++x) {
    for (size_t y = 0; y < n; ++y) {
      for (size_t z = 0; z < n; ++z) {
237
238
239
        part->x[0] = offset[0] + size * (x + 0.5) / (float)n;
        part->x[1] = offset[1] + size * (y + 0.5) / (float)n;
        part->x[2] = offset[2] + size * (z + 0.5) / (float)n;
240
241
        part->h = size * h / (float)n;
        part->mass = density * volume / count;
242
243
244
245
246

        set_velocity(part, vel, size);
        set_energy_state(part, press, size, density);

        part->id = ++(*partId);
247
248
        part->ti_begin = 0;
        part->ti_end = 1;
249

250
        hydro_first_init_part(part, xpart);
251
        ++part;
252
        ++xpart;
253
254
255
256
257
258
259
260
      }
    }
  }

  /* Cell properties */
  cell->split = 0;
  cell->h_max = h;
  cell->count = count;
261
  cell->gcount = 0;
262
  cell->dx_max = 0.;
Matthieu Schaller's avatar
Matthieu Schaller committed
263
264
265
  cell->width[0] = size;
  cell->width[1] = size;
  cell->width[2] = size;
266
267
268
269
270
271
272
  cell->loc[0] = offset[0];
  cell->loc[1] = offset[1];
  cell->loc[2] = offset[2];

  cell->ti_end_min = 1;
  cell->ti_end_max = 1;

273
  // shuffle_particles(cell->parts, cell->count);
274
275
276
277
278
279
280
281
282
283

  cell->sorted = 0;
  cell->sort = NULL;
  cell->sortsize = 0;

  return cell;
}

void clean_up(struct cell *ci) {
  free(ci->parts);
284
  free(ci->xparts);
285
286
287
288
289
290
291
292
  free(ci->sort);
  free(ci);
}

/**
 * @brief Dump all the particles to a file
 */
void dump_particle_fields(char *fileName, struct cell *main_cell,
293
                          struct solution_part *solution, int with_solution) {
294
295
296
297
  FILE *file = fopen(fileName, "w");

  /* Write header */
  fprintf(file,
298
299
300
301
302
          "# %4s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s "
          "%8s %8s %8s %8s %8s\n",
          "ID", "pos_x", "pos_y", "pos_z", "v_x", "v_y", "v_z", "h", "rho",
          "div_v", "S", "u", "P", "c", "a_x", "a_y", "a_z", "h_dt", "v_sig",
          "dS/dt", "du/dt");
303
304
305
306
307
308

  fprintf(file, "# Main cell --------------------------------------------\n");

  /* Write main cell */
  for (size_t pid = 0; pid < main_cell->count; pid++) {
    fprintf(file,
309
310
311
            "%6llu %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f "
            "%8.5f "
            "%8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f\n",
312
313
314
            main_cell->parts[pid].id, main_cell->parts[pid].x[0],
            main_cell->parts[pid].x[1], main_cell->parts[pid].x[2],
            main_cell->parts[pid].v[0], main_cell->parts[pid].v[1],
315
            main_cell->parts[pid].v[2], main_cell->parts[pid].h,
Matthieu Schaller's avatar
Matthieu Schaller committed
316
317
            main_cell->parts[pid].rho,
#ifdef MINIMAL_SPH
Matthieu Schaller's avatar
Matthieu Schaller committed
318
            0.f,
Matthieu Schaller's avatar
Matthieu Schaller committed
319
#else
Matthieu Schaller's avatar
Matthieu Schaller committed
320
321
            main_cell->parts[pid].density.div_v,
#endif
322
323
324
325
326
327
            hydro_get_entropy(&main_cell->parts[pid], 0.f),
            hydro_get_internal_energy(&main_cell->parts[pid], 0.f),
            hydro_get_pressure(&main_cell->parts[pid], 0.f),
            hydro_get_soundspeed(&main_cell->parts[pid], 0.f),
            main_cell->parts[pid].a_hydro[0], main_cell->parts[pid].a_hydro[1],
            main_cell->parts[pid].a_hydro[2], main_cell->parts[pid].force.h_dt,
328
#if defined(GADGET2_SPH)
329
330
            main_cell->parts[pid].force.v_sig, main_cell->parts[pid].entropy_dt,
            0.f
331
#elif defined(DEFAULT_SPH)
332
333
            main_cell->parts[pid].force.v_sig, 0.f,
            main_cell->parts[pid].force.u_dt
Matthieu Schaller's avatar
Matthieu Schaller committed
334
#elif defined(MINIMAL_SPH)
335
            main_cell->parts[pid].force.v_sig, 0.f, main_cell->parts[pid].u_dt
336
#else
337
            0.f, 0.f, 0.f
338
#endif
Matthieu Schaller's avatar
Matthieu Schaller committed
339
            );
340
341
  }

342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
  if (with_solution) {

    fprintf(file, "# Solution ---------------------------------------------\n");

    for (size_t pid = 0; pid < main_cell->count; pid++) {
      fprintf(file,
              "%6llu %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f "
              "%8.5f %8.5f "
              "%8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f %8.5f\n",
              solution[pid].id, solution[pid].x[0], solution[pid].x[1],
              solution[pid].x[2], solution[pid].v[0], solution[pid].v[1],
              solution[pid].v[2], solution[pid].h, solution[pid].rho,
              solution[pid].div_v, solution[pid].S, solution[pid].u,
              solution[pid].P, solution[pid].c, solution[pid].a_hydro[0],
              solution[pid].a_hydro[1], solution[pid].a_hydro[2],
357
358
              solution[pid].h_dt, solution[pid].v_sig, solution[pid].S_dt,
              solution[pid].u_dt);
359
360
    }
  }
361

362
363
364
365
366
367
  fclose(file);
}

/* Just a forward declaration... */
void runner_dopair1_density(struct runner *r, struct cell *ci, struct cell *cj);
void runner_doself1_density(struct runner *r, struct cell *ci);
368
369
void runner_dopair2_force(struct runner *r, struct cell *ci, struct cell *cj);
void runner_doself2_force(struct runner *r, struct cell *ci);
370
371
372

/* And go... */
int main(int argc, char *argv[]) {
373

374
  size_t runs = 0, particles = 0;
375
  double h = 1.23485, size = 1., rho = 2.5;
376
377
  char outputFileNameExtension[200] = "";
  char outputFileName[200] = "";
378
379
  enum velocity_field vel = velocity_zero;
  enum pressure_field press = pressure_const;
380
381
382
383
384

  /* Initialize CPU frequency, this also starts time. */
  unsigned long long cpufreq = 0;
  clocks_set_cpufreq(cpufreq);

385
  /* Choke on FP-exceptions */
386
  feenableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW);
387

388
389
390
391
  /* Get some randomness going */
  srand(0);

  char c;
392
  while ((c = getopt(argc, argv, "m:s:h:n:r:t:d:f:v:p:")) != -1) {
393
394
395
396
397
398
399
    switch (c) {
      case 'h':
        sscanf(optarg, "%lf", &h);
        break;
      case 's':
        sscanf(optarg, "%lf", &size);
        break;
400
      case 'n':
401
402
403
404
405
406
407
408
409
410
411
        sscanf(optarg, "%zu", &particles);
        break;
      case 'r':
        sscanf(optarg, "%zu", &runs);
        break;
      case 'm':
        sscanf(optarg, "%lf", &rho);
        break;
      case 'f':
        strcpy(outputFileNameExtension, optarg);
        break;
412
413
414
415
416
417
      case 'v':
        sscanf(optarg, "%d", (int *)&vel);
        break;
      case 'p':
        sscanf(optarg, "%d", (int *)&press);
        break;
418
419
420
421
422
423
424
425
      case '?':
        error("Unknown option.");
        break;
    }
  }

  if (h < 0 || particles == 0 || runs == 0) {
    printf(
426
427
428
429
430
        "\nUsage: %s -n PARTICLES_PER_AXIS -r NUMBER_OF_RUNS [OPTIONS...]\n"
        "\nGenerates 125 cells, filled with particles on a Cartesian grid."
        "\nThese are then interacted using runner_dopair1_density() and "
        "runner_doself1_density() followed by runner_dopair2_force() and "
        "runner_doself2_force()"
431
432
433
434
        "\n\nOptions:"
        "\n-h DISTANCE=1.2348 - Smoothing length in units of <x>"
        "\n-m rho             - Physical density in the cell"
        "\n-s size            - Physical size of the cell"
435
        "\n-v type (0,1,2,3)  - Velocity field: (zero, constant, divergent, "
436
        "rotating)"
437
        "\n-p type (0,1,2)    - Pressure field: (constant, gradient divergent)"
438
439
440
441
442
443
        "\n-f fileName        - Part of the file name used to save the dumps\n",
        argv[0]);
    exit(1);
  }

  /* Help users... */
444
  message("Adiabatic index: ga = %f", hydro_gamma);
445
  message("Hydro implementation: %s", SPH_IMPLEMENTATION);
446
447
  message("Smoothing length: h = %f", h * size);
  message("Kernel:               %s", kernel_name);
448
  message("Neighbour target: N = %f", pow_dimension(h) * kernel_norm);
449
  message("Density target: rho = %f", rho);
450
451
452
453
454
455
456
457
458
  message("div_v target:   div = %f", vel == 2 ? 3.f : 0.f);
  message("curl_v target: curl = [0., 0., %f]", vel == 3 ? -2.f : 0.f);
  if (press == pressure_const)
    message("P field constant");
  else if (press == pressure_gradient)
    message("P field gradient");
  else
    message("P field divergent");

459
460
  printf("\n");

461
462
463
464
#if !defined(HYDRO_DIMENSION_3D)
  message("test125cells only useful in 3D. Change parameters in const.h !");
  return 1;
#endif
Matthieu Schaller's avatar
Matthieu Schaller committed
465

466
467
468
469
470
  /* Build the infrastructure */
  struct space space;
  space.periodic = 0;
  space.h_max = h;

471
472
473
  struct phys_const prog_const;
  prog_const.const_newton_G = 1.f;

474
  struct hydro_props hp;
475
476
  hp.target_neighbours = pow_dimension(h) * kernel_norm;
  hp.delta_neighbours = 2.;
477
  hp.max_smoothing_iterations = 1;
478
  hp.CFL_condition = 0.1;
479

480
  struct engine engine;
481
  engine.hydro_properties = &hp;
482
  engine.physical_constants = &prog_const;
483
484
485
486
487
488
489
490
  engine.s = &space;
  engine.time = 0.1f;
  engine.ti_current = 1;

  struct runner runner;
  runner.e = &engine;

  /* Construct some cells */
491
492
  struct cell *cells[125];
  struct cell *inner_cells[27];
493
  struct cell *main_cell;
494
  int count = 0;
495
  static long long partId = 0;
496
497
498
499
500
501
502
503
504
  for (int i = 0; i < 5; ++i) {
    for (int j = 0; j < 5; ++j) {
      for (int k = 0; k < 5; ++k) {

        /* Position of the cell */
        const double offset[3] = {i * size, j * size, k * size};

        /* Construct it */
        cells[i * 25 + j * 5 + k] =
505
            make_cell(particles, offset, size, h, rho, &partId, vel, press);
506
507
508
509
510
511

        /* Store the inner cells */
        if (i > 0 && i < 4 && j > 0 && j < 4 && k > 0 && k < 4) {
          inner_cells[count] = cells[i * 25 + j * 5 + k];
          count++;
        }
512
513
514
515
516
      }
    }
  }

  /* Store the main cell for future use */
517
  main_cell = cells[62];
518

519
520
521
522
523
524
  /* Construct the real solution */
  struct solution_part *solution =
      malloc(main_cell->count * sizeof(struct solution_part));
  get_solution(main_cell, solution, rho, vel, press, size);

  /* Start the test */
525
526
527
528
529
  ticks time = 0;
  for (size_t i = 0; i < runs; ++i) {

    const ticks tic = getticks();

530
531
532
533
534
535
    /* First, sort stuff */
    for (int j = 0; j < 125; ++j) runner_do_sort(&runner, cells[j], 0x1FFF, 0);

    /* Initialise the particles */
    for (int j = 0; j < 125; ++j) runner_do_init(&runner, cells[j], 0);

536
/* Do the density calculation */
537
#if !(defined(MINIMAL_SPH) && defined(WITH_VECTORIZATION))
538

539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
    /* Run all the pairs (only once !)*/
    for (int i = 0; i < 5; i++) {
      for (int j = 0; j < 5; j++) {
        for (int k = 0; k < 5; k++) {

          struct cell *ci = cells[i * 25 + j * 5 + k];

          for (int ii = -1; ii < 2; ii++) {
            int iii = i + ii;
            if (iii < 0 || iii >= 5) continue;
            iii = (iii + 5) % 5;
            for (int jj = -1; jj < 2; jj++) {
              int jjj = j + jj;
              if (jjj < 0 || jjj >= 5) continue;
              jjj = (jjj + 5) % 5;
              for (int kk = -1; kk < 2; kk++) {
                int kkk = k + kk;
                if (kkk < 0 || kkk >= 5) continue;
                kkk = (kkk + 5) % 5;

                struct cell *cj = cells[iii * 25 + jjj * 5 + kkk];

                if (cj > ci) runner_dopair1_density(&runner, ci, cj);
              }
            }
          }
        }
      }
    }

    /* And now the self-interaction for the central cells*/
570
    for (int j = 0; j < 27; ++j)
571
572
573
      runner_doself1_density(&runner, inner_cells[j]);

#endif
574

575
576
577
578
    /* Ghost to finish everything on the central cells */
    for (int j = 0; j < 27; ++j) runner_do_ghost(&runner, inner_cells[j]);

/* Do the force calculation */
579
#if !(defined(MINIMAL_SPH) && defined(WITH_VECTORIZATION))
580

581
582
583
584
585
586
587
588
589
590
591
592
593
594
    /* Do the pairs (for the central 27 cells) */
    for (int i = 1; i < 4; i++) {
      for (int j = 1; j < 4; j++) {
        for (int k = 1; k < 4; k++) {

          struct cell *cj = cells[i * 25 + j * 5 + k];

          if (main_cell != cj) runner_dopair2_force(&runner, main_cell, cj);
        }
      }
    }

    /* And now the self-interaction for the main cell */
    runner_doself2_force(&runner, main_cell);
595
596
#endif

597
598
599
    /* Finally, give a gentle kick */
    runner_do_kick(&runner, main_cell, 0);

600
601
602
603
    const ticks toc = getticks();
    time += toc - tic;

    /* Dump if necessary */
604
    if (i == 0) {
605
      sprintf(outputFileName, "swift_dopair_125_%s.dat",
606
              outputFileNameExtension);
607
      dump_particle_fields(outputFileName, main_cell, solution, 0);
608
609
610
611
612
613
    }
  }

  /* Output timing */
  message("SWIFT calculation took       : %15lli ticks.", time / runs);

614
615
616
  for (int j = 0; j < 125; ++j)
    reset_particles(cells[j], vel, press, size, rho);

617
618
619
620
621
622
623
624
  /* NOW BRUTE-FORCE CALCULATION */

  const ticks tic = getticks();

  /* Initialise the particles */
  for (int j = 0; j < 125; ++j) runner_do_init(&runner, cells[j], 0);

/* Do the density calculation */
625
#if !(defined(MINIMAL_SPH) && defined(WITH_VECTORIZATION))
626

627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
  /* Run all the pairs (only once !)*/
  for (int i = 0; i < 5; i++) {
    for (int j = 0; j < 5; j++) {
      for (int k = 0; k < 5; k++) {

        struct cell *ci = cells[i * 25 + j * 5 + k];

        for (int ii = -1; ii < 2; ii++) {
          int iii = i + ii;
          if (iii < 0 || iii >= 5) continue;
          iii = (iii + 5) % 5;
          for (int jj = -1; jj < 2; jj++) {
            int jjj = j + jj;
            if (jjj < 0 || jjj >= 5) continue;
            jjj = (jjj + 5) % 5;
            for (int kk = -1; kk < 2; kk++) {
              int kkk = k + kk;
              if (kkk < 0 || kkk >= 5) continue;
              kkk = (kkk + 5) % 5;

              struct cell *cj = cells[iii * 25 + jjj * 5 + kkk];

              if (cj > ci) pairs_all_density(&runner, ci, cj);
            }
          }
        }
      }
    }
  }
656

657
658
  /* And now the self-interaction for the central cells*/
  for (int j = 0; j < 27; ++j) self_all_density(&runner, inner_cells[j]);
659

660
#endif
661

662
663
  /* Ghost to finish everything on the central cells */
  for (int j = 0; j < 27; ++j) runner_do_ghost(&runner, inner_cells[j]);
664

665
/* Do the force calculation */
666
#if !(defined(MINIMAL_SPH) && defined(WITH_VECTORIZATION))
667

668
669
670
671
  /* Do the pairs (for the central 27 cells) */
  for (int i = 1; i < 4; i++) {
    for (int j = 1; j < 4; j++) {
      for (int k = 1; k < 4; k++) {
672

673
674
675
676
677
678
679
680
681
        struct cell *cj = cells[i * 25 + j * 5 + k];

        if (main_cell != cj) pairs_all_force(&runner, main_cell, cj);
      }
    }
  }

  /* And now the self-interaction for the main cell */
  self_all_force(&runner, main_cell);
682

683
#endif
684

685
686
  /* Finally, give a gentle kick */
  runner_do_kick(&runner, main_cell, 0);
687

688
  const ticks toc = getticks();
689

690
691
  /* Output timing */
  message("Brute force calculation took : %15lli ticks.", toc - tic);
692

693
694
  sprintf(outputFileName, "brute_force_125_%s.dat", outputFileNameExtension);
  dump_particle_fields(outputFileName, main_cell, solution, 0);
695
696

  /* Clean things to make the sanitizer happy ... */
697
  for (int i = 0; i < 125; ++i) clean_up(cells[i]);
698
  free(solution);
699
700
701

  return 0;
}