get_distribution.m

function [ S0, S1, sigma ] = get_distribution( mean, choice, CX2, decay )
 
% return the MAP representation (S0,S1) of the required distribution
% mean: mean rate of the distribution
% choice: the targeted distribution, where 1 = Exp, 2 = HE2,
% 3 = ER2, 4 = MAP2
 
if (choice == 4)
        
    % 2-phase MAP arrivals: MAP2
    [ lambda1,lambda2,a ] = estimateH2( mean, CX2 );
    [ S0, S1, p ] = map2( lambda1, lambda2, a, decay);
    sigma = [p,1-p];
    
else
    if (choice == 1)
        % Exponential distribution:Exp
        S = -mean;
        s = mean;
        sigma = 1;
        
    elseif (choice == 2)
        % 2-phase Hyper-exponential distribution: HE2
        [ lambda1,lambda2,a ] = estimateH2( mean, CX2 );
        S = [-lambda1,0; 0,-lambda2];
        s = [lambda1; lambda2];
        sigma = [a,1-a];
        
    elseif (choice == 3)
        % 2-phase Erlang distribution: ER2
        v = 2*mean;
        S = [-v,v;0,-v];
        s = [0;v];
        sigma = [1,0];
        
    end
    
    S0 = S;
    S1 = s*sigma;
    
end