s2rout3.m

Industrial Mathematics

% Routine 2.3 
a = 10;                 % arrival time parameter
m = 3;                   % number of processors
mu = 20;                 % mean processing time
sig = 1;                 % s.d. of the processing time
Q = 1:m;                 % set the # processors = m
Q = 0*Q;                 % initialize the queue of m processors
t = 0;                   % set the timeclock to zero
rej = 0;                 % set reject count to 0
N = 10000;               % watch for N arrivals
for k=1:N                % begin the experiment
 busy = 1;               % set `all busy' toggle
 T = -a*log(1-rand);     % arrival time of new customer
 t = t + T;              % update the timeclock to present
 for i=1:m               % check to see who's busy:
   if Q(i) < t           % if i is free, then
     S = mu+sig*randn;   % compute time to service,
     Q(i) = t+ S;        % put i to work servicing the request,
     busy=0;             % and signal no reject necessary,
     break;              % then escape to wait for next arrival.
     end;                % endif
  end;                   % stop canvassing processors
if busy==1               % if all processors were busy then
  rej = rej+1;           % increment the number of rejects.
  end;                   % endif
end;                     % end experiment
rej/N                    % print the ratio of rejects