function period = lcg_gen(fig_name,a,c,m,x0,maxnum,viewport,pause_val,do_trace)
figure('Name',fig_name);
grid on
axis([0 m*viewport 0 m*viewport]);
hold on;

count=1;
xnmin1=x0;
to_display=viewport*m;
while count <= maxnum
   xn=mod(a*xnmin1+c,m);
   if xn<=to_display
      plot(xn,xnmin1,'-ok','MarkerSize',3,'MarkerFaceColor',[0,0,0]);
      if do_trace>0
         s = sprintf('Count:%03d Xn-1:%03d Xn:%03d',count,xnmin1,xn);
         disp(s);
      end
      if pause_val>=0 
         if pause_val>0 
            pause(pause_val);   
         else 
            pause;   
         end
      end
   end
   if xn==x0 break, end  
   xnmin1=xn;
   count = count+1;
end
s = sprintf('PRE LCG(a,c,m,x0)=LCG(%d,%d,%d,%d) zobrazenych %d bodov',a,c,m,x0,count);
disp(s)
ret=count;
return