%阻塞率的理論值計算
function[busy_r]=busy_rate(mean_arr,mean_serv,server_num)
C=server_num;
A=mean_serv/mean_arr;  
%到達速率與服務速率之比等于單位服務時間與單位到達時間之比
sum=0;
for k=0:C-1
    sum=sum+A^k/jiecheng(k);
end
%前提mean_serv/mean_arr<C
busy_r=(A^C)/((A^C)+jiecheng(C)*(1-A/C)*sum);