| #include <stdio.h> |
| #include <math.h> |
| #include <gsl/gsl_rng.h> |
| #include <gsl/gsl_randist.h> |
| #define OUT_FILE “out_seq.txt” //results |
| #define MC 20 //number of Monte-Carlo simulations |
| #define N 1000 //number of clients |
| #define M 5 //number of servicing phases |
| //parameters of the exponential distributions |
| int lambda[M + 1] = {0}; |
| double tau = 0; //interarrival time |
| double st = 0; //sojourn time |
| //sojourn time for the previous client |
| double st_prev[M] = {0}; |
| //sojourn time for each MC trial |
| double results[MC] = {0}; |
| int main(int argc, char argv) { |
| gsl_rng ran; //random generator |
| gsl_rng_env_setup(); |
| ran = gsl_rng_alloc(gsl_rng_ranlxs2); |
| //init lambda (heavy traffic case) |
| lambda0] = 30000; |
| for (int i = 1; i < M; i++)lambda[i] = lambda[i − 1] − 25000/M; |
| lambda[M] = 5000; |
| for (unsigned j = 0; j < MC; j++) { |
| tau = gsl_ran_exponential(ran, 1.0/lambda0); |
| st = 0; |
| for (unsigned i = 0; i < M; i++) st_prev[i] = 0.; |
| for (unsigned i = 0; i < N; i++) { |
| for (unsigned t = 0; t < M; t++) { |
| //recurrent equation |
| st += gsl_ran_exponential(ran, 1.0/lambda[t + 1]) + fmax(0.0, st_prev[t] − st − tau); |
| st_prev[t] = st; |
|
| results [j] = st; |
| } |
| //printing results to file |
| FILE fp; |
| const char DATA_FILE = OUT_FILE; |
| fp = fopen(DATA_FILE, “w”); |
| fprintf(fp, “%d%s%d%s%dn”, N, “,”, lambda0, “,”, lambda[M]); |
| for (int i = 0; i < MC − 1; i++) fprintf(fp, “%f%s”, results[i], “,”); |
| fprintf(fp, “%fn”, results[MC − 1]); |
| fclose(fp); |
| gsl_rng_free(ran); |
| return(0); |
| } |
