
% Copyright 2015 The MathWorks, Inc.

function [A,B,C,D,Mean0,Cov0,StateType] = timeVariantParamMap(params)
% Time-variant state-space model parameter mapping function example. This
% function maps the vector params to the state-space matrices (A, B, C, and
% D), the initial state value and the initial state variance (Mean0 and
% Cov0), and the type of state (StateType). From periods 1 through 10, the
% state model is an AR(2) and an MA(1) model, and the observation model is
% the sum of the two states. From periods 11 through 20, the state model is
% just the AR(2) model.
    varu11 = exp(params(3));  % Positive variance constraints
    vare11 = exp(params(6));
    vare12 = exp(params(8));
    A1 = {[params(1) params(2) 0 0; 1 0 0 0; 0 0 0 params(4); 0 0 0 0]};
    B1 = {[sqrt(varu11) 0; 0 0; 0 1; 0 1]}; 
    C1 = {params(5)*[1 0 1 0]};
    D1 = {sqrt(vare11)};
    Mean0 = [0.5 0.5 0 0];
    Cov0 = eye(4);
    StateType = [0 0 0 0];
    A2 = {[params(1) params(2) 0 0; 1 0 0 0]};
    B2 = {[sqrt(varu11); 0]};
    A3 = {[params(1) params(2); 1 0]};
    B3 = {[sqrt(varu11); 0]}; 
    C3 = {params(7)*[1 0]};
    D3 = {sqrt(vare12)};
    A = [repmat(A1,10,1);A2;repmat(A3,9,1)];
    B = [repmat(B1,10,1);B2;repmat(B3,9,1)];
    C = [repmat(C1,10,1);repmat(C3,10,1)];
    D = [repmat(D1,10,1);repmat(D3,10,1)];
end
