#define MAXBUF 100000
#define MAXVAL 10

void graph(char *filename)
{
  FILE *fp;
  char buf[256];
  double x[MAXBUF],y[MAXBUF];
  int i;

  fp = fopen(filename, "r");
  if (!fp) {
    fprintf(stderr,"cannot open %s\n",filename);
  }

  i=0;
  while (1) {
    if (fgets(buf, sizeof(buf), fp)==NULL)
      break;
    if (buf[0] == '#' || buf[0] == '\n')
      continue;
    sscanf(buf,"%lf %lf", &x[i], &y[i]);
    i++;
  }

  TGraph *gr = new TGraph(i, x, y);
  gr->SetTitle("");
  gr->SetName("gr");
  gr->SetMarkerColor(kBlue);
  gr->SetMarkerStyle(20);
  gr->SetMarkerSize(0.7);
  gr->Draw("ap");
}