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main.c
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main.c
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/* Heat equation solver in 2D. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <mpi.h>
#include "heat.h"
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; //!< Number of time steps
int image_interval = 500; //!< Image output interval
int restart_interval = 200; //!< Checkpoint output interval
parallel_data parallelization; //!< Parallelization info
int iter, iter0; //!< Iteration counter
double dx2, dy2; //!< delta x and y squared
double start_clock; //!< Time stamps
MPI_Init(&argc, &argv);
initialize(argc, argv, ¤t, &previous, &nsteps,
¶llelization, &iter0);
/* Output the initial field */
write_field(¤t, iter0, ¶llelization);
iter0++;
/* Largest stable time step */
dx2 = current.dx * current.dx;
dy2 = current.dy * current.dy;
dt = dx2 * dy2 / (2.0 * a * (dx2 + dy2));
/* Get the start time stamp */
start_clock = MPI_Wtime();
/* Time evolve */
for (iter = iter0; iter < iter0 + nsteps; iter++) {
exchange_init(&previous, ¶llelization);
evolve_interior(¤t, &previous, a, dt);
exchange_finalize(¶llelization);
evolve_edges(¤t, &previous, a, dt);
if (iter % image_interval == 0) {
write_field(¤t, iter, ¶llelization);
}
/* write a checkpoint now and then for easy restarting */
if (iter % restart_interval == 0) {
write_restart(¤t, ¶llelization, iter);
}
/* Swap current field so that it will be used
as previous for next iteration step */
swap_fields(¤t, &previous);
}
/* Determine the CPU time used for the iteration */
if (parallelization.rank == 0) {
printf("Iteration took %.3f seconds.\n", (MPI_Wtime() - start_clock));
printf("Reference value at 5,5: %f\n",
previous.data[idx(5, 5, current.ny + 2)]);
}
write_field(¤t, iter, ¶llelization);
finalize(¤t, &previous, ¶llelization);
MPI_Finalize();
return 0;
}