gistfile1.txt

function poisson(k, landa) {
    exponentialPower = Math.exp(-landa); // negative power k
    landaPowerK = Math.pow(landa, k); // Landa elevated k
    numerator = exponentialPower * landaPowerK;
    denominator = fact(k); // factorial of k.
    
    return (numerator / denominator);
}

function fact(x) {
   if(x==0) {
      return 1;
   }
   return x * fact(x-1);
}

function ESPERADO(g_home, xg_home, g_away, xg_away) {
  var rps = 0.0;
  var cdf_xhome = 0.0;
  var cdf_xaway = 0.0;
  var cdf_home = 0.0;
  var cdf_away = 0.0;
  for (var i = 0; i < 10; i++) {
    cdf_xhome += poisson(i, xg_home);
    cdf_xaway += poisson(i, xg_away);
    if (i == g_home) cdf_home += 1.0;
    if (i == g_away) cdf_away += 1.0;
    rps += (cdf_xhome - cdf_home) * (cdf_xhome - cdf_home);
    rps += (cdf_away - cdf_away) * (cdf_xaway - cdf_away);
  }
  return rps / 9;
}

function JUSTICA(g_home, xg_home, g_away, xg_away) {
  var cdf_x = 0.0;
  var cdf_y = 0.0;
  var rps = 0.0;
  for (var i = -9; i < 10; i++) {
    for (var j = 0; j < 10; j++) {
      for (var k = 0; k < 10; k++) {
        if (j - k != i) continue;
        cdf_x += poisson(j, xg_home) * poisson(k, xg_away);
        if (j == g_home && k == g_away) {
          cdf_y += 1.0;
        }
      }
    }
    rps += (cdf_x - cdf_y) * (cdf_x - cdf_y)
  }
  return rps / 18;
}