%--------------------------------------------------------------------
% lcr_sim.m ---------------------------------------------------------
%
% Program for the computation of the level-crossing rate N(r).
%
%--------------------------------------------------------------------
% N_r=lcr_sim(xi_t,r,T_sim,PLOT)
%--------------------------------------------------------------------
% Explanation of the input parameters:
%
% xi_t: deterministic process or time-domain signal to be analysed 
%       with respect to the level-crossing rate N(r)
% r: level vector
% T_sim: duration of the simulation
% PLOT: plot of the resulting level-crossing rate N(r), if PLOT==1

function N_r=lcr_sim(xi_t,r,T_sim,PLOT)

if nargin==3,
   PLOT=0;
end

N_r=zeros(size(r));

for k=1:length(r),
    N_r(k)=sum(xi_t(2:length(xi_t)) < r(k) & ...
               xi_t(1:length(xi_t)-1) >= r(k) );
end

N_r=N_r/T_sim;

if PLOT==1,
   plot(r,N_r,'yx')
   xlabel('r')
   ylabel('N(r)')
end