LagkJointMomentsFromDRAP.m

%  Nm = LagkJointMomentsFromDRAP(H0, H1, K, L, prec)
%  
%  Returns the lag-L joint moments of a discrete rational 
%  arrival process.
%  
%  Parameters
%  ----------
%  H0 : matrix, shape (M,M)
%      The H0 matrix of the discrete rational arrival process
%  H1 : matrix, shape (M,M)
%      The H1 matrix of the discrete rational arrival process
%  K : int, optional
%      The dimension of the matrix of joint moments to 
%      compute. If K=0, the MxM joint moments will be 
%      computed. The default value is 0
%  L : int, optional
%      The lag at which the joint moments are computed.
%      The default value is 1
%  prec : double, optional
%      Numerical precision to check if the input is valid. 
%      The default value is 1e-14
%  
%  Returns
%  -------
%  Nm : matrix, shape(K+1,K+1)
%      The matrix containing the lag-L joint moments, 
%      starting from moment 0.
 
function [Nm] = LagkJointMomentsFromDRAP (d0, d1, K, L)
 
    global BuToolsCheckInput;
    if isempty(BuToolsCheckInput)
        BuToolsCheckInput = true;
    end   
 
    if BuToolsCheckInput && ~CheckDRAPRepresentation(d0,d1)
        error('LagkJointMomentsFromDRAP: Input isn''t a valid DRAP representation!');
    end
 
    h{1}=d0;
    h{2}=d1;
 
    if ~exist('K','var')
        K=size(h{1},1)-1;
    end
 
    if ~exist('L','var')
        L=1;
    end
 
    mom=LagkJointMomentsFromDMRAP(h,K,L);
    Nm=mom{1};
end