gas.c

#include <stdlib.h>
#include <stdio.h>

#define MEM_ERROR -2
#define ERROR -9
#define SUCCESS 0


struct particle {
  int label;
  char *loc;
  int xdist;
  int ydist;
};


int myRand(int a, int b);


int main(int argc, char **argv) {
  int i, j, k, steps, L, N, plab;
  char *grill;
  unsigned long long int seed;
  double boh;
  struct particle *gas;
  FILE *fout=fopen("gas.dat", "w");

  sscanf(argv[1], "%d", &L);
  sscanf(argv[2], "%Lu", &seed);
  sscanf(argv[3], "%d", &N);
  sscanf(argv[4], "%d", &steps);

  gas=(struct particle *) malloc(N*sizeof(struct particle));
  grill=(char *) calloc(L*L, sizeof(int));
  if (gas==NULL || grill==NULL) {
    printf("\n\nErrore nell'assegnazione della memoria!!\n\n");
    exit(MEM_ERROR);
  }
  srand48(seed);

  /*
  for(i=0; i<N; i++) {
    do {
      plab=myRand(0, L*L);
    } while (grill[plab]!=0);
    grill[plab]=1;
  }
  */

  for (i=0; i<N; i++) {
    gas[i].label=i;
    do {
      plab=myRand(0, L*L);
    } while (grill[plab]!=0);
    grill[plab]=1;
    gas[i].loc=&grill[plab];
  }

  for (k=0; k<steps; k++) {
    plab=myRand(0, N);
    boh=drand48();
    if (boh>0.75) {
      if (*(gas[plab].loc-L)==0) {
    *(gas[plab].loc-L)=1;
    *gas[plab].loc=0;
    gas[plab].loc=gas[plab].loc-L;
    gas[plab].ydist+=1;
      }
    } else if (boh>0.5) {
      if (*(gas[plab].loc+1)==0) {
        *(gas[plab].loc+1)=1;
    *gas[plab].loc=0;
    gas[plab].loc=gas[plab].loc+1;
    gas[plab].xdist+=1;
      }
    } else if (boh>0.25) {
      if (*(gas[plab].loc+L)==0) {
    *(gas[plab].loc+L)=1;
    *gas[plab].loc=0;
    gas[plab].loc=gas[plab].loc+L;
    gas[plab].ydist-=1;
      }
    } else {
      if (*(gas[plab].loc-1)==0) {
    *(gas[plab].loc-1)=1;
    *gas[plab].loc=0;
    gas[plab].loc=gas[plab].loc-1;
    gas[plab].xdist-=1;
      }
    }

    for (i=0; i<L; i++) {
      for (j=0; j<L; j++) {
    fprintf(fout, "%d ", grill[i*L+j]);
      }
      fprintf(fout, "\n");
    }
    fprintf(fout, "\n");
    fflush(fout);
  }

  /*
  for (i=0; i<L; i++) {
    for (j=0; j<L; j++) {
      fprintf(fout, "%d ", grill[i*L+j]);
    }
    fprintf(fout, "\n");
  }
  */

  free(grill);
  free(gas);

return SUCCESS;
}



int myRand(int a, int b) {
  return (int)(a+(b-a)*(double) lrand48()/RAND_MAX);
}