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/* I/O related functions for heat equation solver */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "heat.h"
#include "pngwriter.h"
/* Output routine that prints out a picture of the temperature
* distribution. */
void write_field(field *temperature, int iter)
{
char filename[64];
/* The actual write routine takes only the actual data
* (without ghost layers) so we need array for that. */
int height, width;
double **full_data;
int i;
height = temperature->nx;
width = temperature->ny;
/* Copy the inner data */
full_data = malloc_2d(height, width);
for (i = 0; i < temperature->nx; i++)
memcpy(full_data[i], &temperature->data[i + 1][1],
temperature->ny * sizeof(double));
sprintf(filename, "%s_%04d.png", "heat", iter);
save_png(full_data[0], height, width, filename, 'c');
free_2d(full_data);
}
/* Read the initial temperature distribution from a file and
* initialize the temperature fields temperature1 and
* temperature2 to the same initial state. */
void read_field(field *temperature1, field *temperature2, char *filename)
{
FILE *fp;
int nx, ny, i, j;
int count;
fp = fopen(filename, "r");
/* Read the header */
count = fscanf(fp, "# %d %d \n", &nx, &ny);
if (count < 2) {
fprintf(stderr, "Error while reading the input file!\n");
exit(EXIT_FAILURE);
}
set_field_dimensions(temperature1, nx, ny);
set_field_dimensions(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);
}