void read_input(field * temperature1, field * temperature2, char *filename)
{
FILE *fp;
int nx, ny, i, j;
fp = fopen(filename, "r");
// Read the header
fscanf(fp, "# %d %d \n", &nx, &ny);
initialize_field_metadata(temperature1, nx, ny);
initialize_field_metadata(temperature2, nx, ny);
// Allocate arrays (including ghost layers
temperature1->data = malloc_2d(nx + 2, ny + 2);
temperature2->data = malloc_2d(nx + 2, ny + 2);
// Read the actual data
for (i = 1; i < nx + 1; i++) {
for (j = 1; j < ny + 1; j++) {
fscanf(fp, "%lf", &temperature1->data[i][j]);
}
}
// Set the boundary values
for (i = 1; i < nx + 1; i++) {
temperature1->data[i][0] = temperature1->data[i][1];
temperature1->data[i][ny + 1] = temperature1->data[i][ny];
}
for (j = 0; j < ny + 2; j++) {
temperature1->data[0][j] = temperature1->data[1][j];
temperature1->data[nx + 1][j] = temperature1->data[nx][j];
}
copy_field(temperature1, temperature2);
fclose(fp);
}
void read_restart(field *temperature, parallel_data *parallel, int *iter)
{
MPI_File fp;
int full_nx, full_ny;
int disp, size;
// initialise MPI metadata with bogus dimensions
parallel_initialize(parallel, 0, 0);
// open file for reading
MPI_File_open(parallel->comm, CHECKPOINT, MPI_MODE_RDONLY,
MPI_INFO_NULL, &fp);
// read grid size and current iteration
MPI_File_read_all(fp, &full_nx, 1, MPI_INT, MPI_STATUS_IGNORE);
MPI_File_read_all(fp, &full_ny, 1, MPI_INT, MPI_STATUS_IGNORE);
MPI_File_read_all(fp, iter, 1, MPI_INT, MPI_STATUS_IGNORE);
// set correct dimensions to MPI metadata
parallel_set_dimensions(parallel, full_nx, full_ny);
// set local dimensions and allocate memory for the data
initialize_field_metadata(temperature, full_nx, full_ny, parallel);
allocate_field(temperature);
// size of the local data including the outermost ghost row if at the
// top or the bottom of the full grid
if ((parallel->rank == 0) || (parallel->rank == parallel->size - 1)) {
size = (temperature->nx + 2) * (temperature->ny + 1);
} else {
size = (temperature->nx + 2) * temperature->ny;
}
// point each MPI task to the correct part of the file
disp = 3 * sizeof(int);
if (parallel->rank > 0) {
disp += (1 + parallel->rank * temperature->ny) *
(temperature->nx + 2) * sizeof(double);
}
// read data simultaneously to all processes
MPI_File_read_at_all(fp, disp, &temperature->data[0][0],
size, MPI_DOUBLE, MPI_STATUS_IGNORE);
// close up shop
MPI_File_close(&fp);
}
int main(int argc, char **argv)
{
double a = 0.5; //!< Diffusion constant
field current, previous; //!< Current and previous temperature fields
double dt; //!< Time step
int nsteps = 500; //!< Number of time steps
int rows = 200; //!< Field dimensions with default values
int cols = 200;
char input_file[64]; //!< Name of the optional input file
int image_interval = 10; //!< Image output interval
int iter;
/* Following combinations of command line arguments are possible:
No arguments: use default field dimensions and number of time steps
One argument: read initial field from a given file
Two arguments: initial field from file and number of time steps
Three arguments: field dimensions (rows,cols) and number of time steps
*/
switch (argc) {
case 1:
// use defaults
initialize_field_metadata(¤t, rows, cols);
initialize_field_metadata(&previous, rows, cols);
initialize(¤t, &previous);
break;
case 2:
// Initial field from a file
strncpy(input_file, argv[1], 64);
read_input(¤t, &previous, input_file);
break;
case 3:
// Initial field from a file
strncpy(input_file, argv[1], 64);
read_input(¤t, &previous, input_file);
// Number of time steps
nsteps = atoi(argv[2]);
break;
case 4:
// Field dimensions
rows = atoi(argv[1]);
cols = atoi(argv[2]);
initialize_field_metadata(¤t, rows, cols);
initialize_field_metadata(&previous, rows, cols);
initialize(¤t, &previous);
// Number of time steps
nsteps = atoi(argv[3]);
break;
default:
printf("Unsupported number of command line arguments\n");
return -1;
}
// Output the initial field
output(¤t, 0);
// Largest stable time step
dt = current.dx2 * current.dy2 /
(2.0 * a * (current.dx2 + current.dy2));
// Time evolve
for (iter = 1; iter < nsteps; iter++) {
evolve(¤t, &previous, a, dt);
// output every 10 iteration
if (iter % image_interval == 0)
output(¤t, iter);
// make current field to be previous for next iteration step
swap_fields(¤t, &previous);
}
finalize(¤t, &previous);
return 0;
}
void read_input(field * temperature1, field * temperature2, char *filename,
parallel_data * parallel)
{
FILE *fp;
int nx, ny, i, j;
double **full_data;
double **inner_data;
int nx_local;
fp = fopen(filename, "r");
// Read the header
fscanf(fp, "# %d %d \n", &nx, &ny);
parallel_initialize(parallel, nx, ny);
initialize_field_metadata(temperature1, nx, ny, parallel);
initialize_field_metadata(temperature2, nx, ny, parallel);
// Allocate arrays (including ghost layers)
temperature1->data =
malloc_2d(temperature1->nx + 2, temperature1->ny + 2);
temperature2->data =
malloc_2d(temperature2->nx + 2, temperature2->ny + 2);
inner_data = malloc_2d(temperature1->nx, temperature1->ny);
if (parallel->rank == 0) {
// Full array
full_data = malloc_2d(nx, ny);
// Read the actual data
for (i = 0; i < nx; i++) {
for (j = 0; j < ny; j++) {
fscanf(fp, "%lf", &full_data[i][j]);
}
}
} else
// dummy array for full data
full_data = malloc_2d(1, 1);
nx_local = temperature1->nx;
MPI_Scatter(full_data[0], nx_local * ny, MPI_DOUBLE, inner_data[0],
nx_local * ny, MPI_DOUBLE, 0, parallel->comm);
// Copy to the array containing also boundaries
for (i = 0; i < nx_local; i++)
memcpy(&temperature1->data[i + 1][1], &inner_data[i][0],
ny * sizeof(double));
// Set the boundary values
for (i = 0; i < nx_local + 1; i++) {
temperature1->data[i][0] = temperature1->data[i][1];
temperature1->data[i][ny + 1] = temperature1->data[i][ny];
}
for (j = 0; j < ny + 2; j++) {
temperature1->data[0][j] = temperature1->data[1][j];
temperature1->data[nx_local + 1][j] =
temperature1->data[nx_local][j];
}
copy_field(temperature1, temperature2);
free_2d(full_data);
free_2d(inner_data);
fclose(fp);
}
void read_input(field * temperature1, field * temperature2, char *filename,
parallel_data * parallel)
{
FILE *fp;
int nx, ny, i, j;
double **full_data;
int coords[2];
int ix, jy, p;
fp = fopen(filename, "r");
// Read the header
fscanf(fp, "# %d %d \n", &nx, &ny);
parallel_initialize(parallel, nx, ny);
initialize_field_metadata(temperature1, nx, ny, parallel);
initialize_field_metadata(temperature2, nx, ny, parallel);
// Allocate arrays (including ghost layers)
temperature1->data =
malloc_2d(temperature1->nx + 2, temperature1->ny + 2);
temperature2->data =
malloc_2d(temperature2->nx + 2, temperature2->ny + 2);
if (parallel->rank == 0) {
// Full array
full_data = malloc_2d(nx, ny);
// Read the actual data
for (i = 0; i < nx; i++) {
for (j = 0; j < ny; j++) {
fscanf(fp, "%lf", &full_data[i][j]);
}
}
// Copy to own local array
for (i = 0; i < temperature1->nx; i++)
memcpy(&temperature1->data[i + 1][1], full_data[i],
temperature1->ny * sizeof(double));
// Send to other processes
for (p = 1; p < parallel->size; p++) {
MPI_Cart_coords(parallel->comm, p, 2, coords);
ix = coords[0] * temperature1->nx;
jy = coords[1] * temperature1->ny;
MPI_Send(&full_data[ix][jy], 1, parallel->subarraytype, p, 44,
parallel->comm);
}
} else
// Receive data
MPI_Recv(&temperature1->data[1][1], 1, parallel->subarraytype, 0,
44, parallel->comm, MPI_STATUS_IGNORE);
// Set the boundary values
for (i = 0; i < temperature1->nx + 1; i++) {
temperature1->data[i][0] = temperature1->data[i][1];
temperature1->data[i][temperature1->ny + 1] =
temperature1->data[i][temperature1->ny];
}
for (j = 0; j < temperature1->ny + 2; j++) {
temperature1->data[0][j] = temperature1->data[1][j];
temperature1->data[temperature1->nx + 1][j] =
temperature1->data[temperature1->nx][j];
}
copy_field(temperature1, temperature2);
if (parallel->rank == 0)
free_2d(full_data);
fclose(fp);
}