You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: infMCMC.m
    path of file: ./repos/hctsa/Toolboxes/gpml/inf
    
    the code of the file until where you have to start completion: function [post nlZ dnlZ] = infMCMC(hyp, mean, cov, lik, x, y, par)

% Markov Chain Monte Carlo (MCMC) sampling from posterior and 
% Annealed Importance Sampling (AIS) for marginal likelihood estimation.
%
% The algorithms are not to be used as a black box, since t
    
function [alpha,Na] = sample_hmc(K,m,y,lik,hyp, N,Nb,Ns, taus)
  % use adaptive stepsize rule to enforce a specific acceptance rate 
  epmin = 1e-6; % minimum leapfrog stepsize
  epmax = 9e-1; % maximum leapfrog stepsize
  ep    = 1e-2; % initial leapfrog stepsize
  acc_t = 0.9;  % target acceptance rate
  acc   = 0;    % current acceptance rate
  epinc = 1.02; % increase factor of stepsize if acceptance rate is below target
  epdec = 0.98; % decrease factor of stepsize if acceptance rate is above target
  lam   = 0.01; %  exponential moving average computation of the acceptance rate
          % 2/(3*lam) steps half height; lam/nstep = 0.02/33, 0.01/66, 0.005/133
  l = 20;       % number of leapfrog steps to perform for one step
  n = size(K,1);
  T = (N+Nb)*Ns;                                       % overall number of steps
  alpha = zeros(n,N);                                            % sample points
  al = zeros(n,1);                                            % current position
  if nargin>=9, tau = taus(1); else tau = 1; end