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87 | #include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <sys/time.h>
#define WIDTH 1000
#define HEIGHT 1000
#define EPSILON 0.01
static double temperature[HEIGHT+2][WIDTH+2];
static double prev_temperature[HEIGHT+2][WIDTH+2];
void initialize(void);
void track_progress(int iter);
int main(void)
{
int iteration = 1;
double worst_dt = 100.0;
struct timeval start_time, stop_time, elapsed_time;
gettimeofday(&start_time,NULL);
initialize();
while ( worst_dt > EPSILON )
{
for(int i = 1; i <= HEIGHT; i++)
{
for(int j = 1; j <= WIDTH; j++)
{
temperature[i][j] = 0.25 * (prev_temperature[i+1][j] + prev_temperature[i-1][j] +
prev_temperature[i][j+1] + prev_temperature[i][j-1]);
}
}
worst_dt = 0.0;
for(int i = 1; i <= HEIGHT; i++)
{
for(int j = 1; j <= WIDTH; j++)
{
worst_dt = fmax( fabs(temperature[i][j]-prev_temperature[i][j]), worst_dt);
prev_temperature[i][j] = temperature[i][j];
}
}
if((iteration % 100) == 0)
track_progress(iteration);
iteration++;
}
gettimeofday(&stop_time,NULL);
timersub(&stop_time, &start_time, &elapsed_time);
printf("\nMax error at iteration %d was %f\n", iteration-1, worst_dt);
printf("Total time was %f seconds.\n", elapsed_time.tv_sec+elapsed_time.tv_usec/1000000.0);
}
void initialize()
{
for(int i = 0; i <= HEIGHT+1; i++)
for (int j = 0; j <= WIDTH+1; j++)
prev_temperature[i][j] = 0.0;
for(int i = 0; i <= HEIGHT+1; i++)
{
prev_temperature[i][0] = 0.0;
prev_temperature[i][WIDTH+1] = (100.0/HEIGHT)*i;
}
for(int j = 0; j <= WIDTH+1; j++)
{
prev_temperature[0][j] = 0.0;
prev_temperature[HEIGHT+1][j] = (100.0/WIDTH)*j;
}
}
void track_progress(int iteration)
{
printf("---------- Iteration number: %d ------------\n", iteration);
for(int i = HEIGHT-5; i <= HEIGHT; i++)
printf("[%d,%d]: %5.2f ", i, i, temperature[i][i]);
printf("\n");
}
|