function x = updatestates(xu,q);% PURPOSE : Performs the resampling step of the SIR algorithm%           in order(numSamples) steps.% INPUTS  : - xu = Predicted state samples.%           - q = Normalised importance ratios.% OUTPUTS : - x = Resampled state samples.% AUTHOR  : Nando de Freitas - Thanks for the acknowledgement :-)% DATE    : 08-09-98if nargin < 2, error('Not enough input arguments.'); end[N,timeStep]=size(xu);  % N = number of samples;u = rand(N+1,1);t = -log(u);x = 10.*ones(size(xu));T = cumsum(t);Q = cumsum(q);i = 1;j = 1;while j <= N,  if (Q(j,1)*T(N,1)) > T(i,1)    x(i,1) = xu(j,1);     i = i+1;  else    j = j+1;  end;end;