Actual source code: ex2.c
1: static char help[] = "Demonstrates Conway's Game of Life using a 2d DMDA.\n\n";
3: /*
4: At each step in time, the following transitions occur:
6: Any live cell with fewer than two live neighbours dies, as if by underpopulation.
7: Any live cell with two or three live neighbours lives on to the next generation.
8: Any live cell with more than three live neighbours dies, as if by overpopulation.
9: Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction.
11: https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life
12: */
14: #include <petscdm.h>
15: #include <petscdmda.h>
17: static const int GLIDER[3][3] = {
18: {0, 1, 0},
19: {0, 1, 1},
20: {1, 0, 1}
21: };
23: int main(int argc, char **argv)
24: {
25: DM da;
26: PetscViewer viewer;
27: Vec Xlocal, Xglobal;
28: PetscInt glider_loc[2] = {10, 20}, blinker_loc[2] = {20, 10}, two, steps = 100, viz_interval = 1;
29: PetscInt check_step_alive = -1, check_step_dead = -1;
30: PetscBool has_glider, has_blinker;
33: PetscInitialize(&argc, &argv, (char *)0, help);
34: PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "Conway's Game of Life", "");
35: {
36: PetscOptionsIntArray("-glider", "Coordinate at which to center a glider", NULL, glider_loc, (two = 2, &two), &has_glider);
37: PetscOptionsIntArray("-blinker", "Coordinate at which to center a blinker", NULL, blinker_loc, (two = 2, &two), &has_blinker);
38: PetscOptionsInt("-steps", "Number of steps to take", NULL, steps, &steps, NULL);
39: PetscOptionsInt("-viz_interval", "Visualization interval", NULL, viz_interval, &viz_interval, NULL);
40: PetscOptionsInt("-check_step_alive", "Step on which to check that the simulation is alive", NULL, check_step_alive, &check_step_alive, NULL);
41: PetscOptionsInt("-check_step_dead", "Step on which to check that the simulation is dead", NULL, check_step_dead, &check_step_dead, NULL);
42: }
43: PetscOptionsEnd();
45: PetscViewerDrawOpen(PETSC_COMM_WORLD, NULL, "Life", PETSC_DECIDE, PETSC_DECIDE, 1000, 1000, &viewer);
47: /* Create distributed array and get vectors */
48: DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_PERIODIC, DM_BOUNDARY_PERIODIC, DMDA_STENCIL_BOX, 30, 30, PETSC_DECIDE, PETSC_DECIDE, 1, 1, NULL, NULL, &da);
49: DMSetFromOptions(da);
50: DMSetUp(da);
51: DMCreateLocalVector(da, &Xlocal);
52: DMCreateGlobalVector(da, &Xglobal);
54: { /* Initialize */
55: DMDALocalInfo info;
56: PetscScalar **x;
57: PetscInt i, j;
59: DMDAGetLocalInfo(da, &info);
60: DMDAVecGetArray(da, Xlocal, &x);
61: for (j = info.ys; j < info.ys + info.ym; j++) {
62: for (i = info.xs; i < info.xs + info.xm; i++) {
63: if (has_glider && i == glider_loc[0] && j == glider_loc[1]) {
64: PetscInt ii, jj;
65: for (ii = -1; ii <= 1; ii++)
66: for (jj = -1; jj <= 1; jj++) x[j + jj][i + ii] = GLIDER[1 - jj][ii + 1];
67: }
68: if (has_blinker && i == blinker_loc[0] && j == blinker_loc[1]) {
69: x[j - 1][i] = 1;
70: x[j][i] = 1;
71: x[j + 1][i] = 1;
72: }
73: }
74: }
75: DMDAVecRestoreArray(da, Xlocal, &x);
76: DMLocalToGlobal(da, Xlocal, ADD_VALUES, Xglobal);
77: }
79: /* View the initial condition */
80: VecView(Xglobal, viewer);
82: { /* Play */
83: PetscInt step;
85: for (step = 0; step < steps; step++) {
86: const PetscScalar **x;
87: PetscScalar **y;
88: DMDALocalInfo info;
89: PetscInt i, j;
91: DMGlobalToLocal(da, Xglobal, INSERT_VALUES, Xlocal);
92: DMDAGetLocalInfo(da, &info);
93: DMDAVecGetArrayRead(da, Xlocal, (void *)&x);
94: DMDAVecGetArrayWrite(da, Xglobal, &y);
95: for (j = info.ys; j < info.ys + info.ym; j++) {
96: for (i = info.xs; i < info.xs + info.xm; i++) {
97: PetscInt live_neighbors = 0;
98: live_neighbors += PetscRealPart(x[j - 1][i - 1]) > 0;
99: live_neighbors += PetscRealPart(x[j - 1][i]) > 0;
100: live_neighbors += PetscRealPart(x[j - 1][i + 1]) > 0;
101: live_neighbors += PetscRealPart(x[j][i - 1]) > 0;
102: live_neighbors += PetscRealPart(x[j][i + 1]) > 0;
103: live_neighbors += PetscRealPart(x[j + 1][i - 1]) > 0;
104: live_neighbors += PetscRealPart(x[j + 1][i]) > 0;
105: live_neighbors += PetscRealPart(x[j + 1][i + 1]) > 0;
106: if (PetscRealPart(x[j][i]) > 0) { /* Live cell */
107: switch (live_neighbors) {
108: case 2:
109: case 3:
110: y[j][i] = 1; /* Survive */
111: break;
112: default:
113: y[j][i] = 0; /* Death */
114: }
115: } else { /* Dead cell */
116: if (live_neighbors == 3) y[j][i] = 1; /* Birth */
117: else y[j][i] = 0;
118: }
119: }
120: }
121: DMDAVecRestoreArrayRead(da, Xlocal, (void *)&x);
122: DMDAVecRestoreArrayWrite(da, Xglobal, &y);
123: if (step == check_step_alive || step == check_step_dead) {
124: PetscScalar sum;
125: VecSum(Xglobal, &sum);
126: if (PetscAbsScalar(sum) > 0.1) {
127: if (step == check_step_dead) PetscPrintf(PETSC_COMM_WORLD, "Simulation alive at step %" PetscInt_FMT "\n", step);
128: } else if (step == check_step_alive) {
129: PetscPrintf(PETSC_COMM_WORLD, "Simulation dead at step %" PetscInt_FMT "\n", step);
130: }
131: }
132: if (step % viz_interval == 0) VecView(Xglobal, viewer);
133: }
134: }
136: PetscViewerDestroy(&viewer);
137: VecDestroy(&Xglobal);
138: VecDestroy(&Xlocal);
139: DMDestroy(&da);
140: PetscFinalize();
141: return 0;
142: }
144: /*TEST
146: test:
147: requires: x
148: nsize: 2
149: args: -glider 5,6 -blinker 12,12 -steps 35 -check_step_alive 31 -check_step_dead 32 -da_grid_x 20 -da_grid_y 20 -nox
151: TEST*/