#include <stdio.h>
#include <math.h>

long state = 5;
long lcg() {
  state = (1103515245L * state + 12345L) % 2147483648L;
  return state;
}
double uniform() { return (double)lcg() / 2147483648.0; }
double exponential(double rate) {
  double u = uniform();
  if (u < 1e-12) u = 1e-12;
  return -log(u) / rate;
}

int main() {
  double lambda = 4.0, mu = 5.0;
  double rho = lambda / mu;
  double theoretical = rho / (1 - rho);
  printf("Analytic M/M/1, rho = %.2f\n", rho);
  printf("Theoretical mean customers in system = %.3f\n", theoretical);
  printf("\nCompare the model output with this value to validate it.\n");
  return 0;
}