function [state_eq, obser_eq, Nx, Ny, Nu, NparSys, Nparam, NparID, dt, Ndata, Nzi, izhf, ...
             t, Z, Uinp, param, parFlag, x0, iArtifStab, StabMat] = mDefCase04(test_case)

% Definition of model, flight data, initial values etc. 
% test_case = 11: Short period motion, nx=2, ny=2, nu=1, test aircraft ATTAS
%                 states  - alpha, q
%                 outputs - alpha, q
%                 inputs  - de 
%
% Inputs
%    test_case    test case number
%
% Outputs
%    state_eq     function to code right hand sides of state equations       
%    obser_eq     function to code right hand sides of observation equations
%    Nx           number of states 
%    Ny           number of observation variables
%    Nu           number of input (control) variables
%    NparSys      number of system parameters
%    Nparam       total number of system and bias parameters
%    NparID       total number of parameters to be estimated (free parameters)
%    dt           sampling time
%    Ndata        total number of data points for Nzi time segments
%    Nzi          number of time segments (maneuvers) to be analyzed simultaneously
%    izhf         cumulative index at which the maneuvers end when concatenated
%    t            time vector
%    Z            observation variables: Data array of measured outputs (Ndata,Ny)
%    Uinp         input variables: Data array of measured input (Ndata,Nu)
%    param        initial starting values for unknown parameters (aerodynamic derivatives) 
%    parFlag      flags for free and fixed parameters
%    x0           initial conditions on state variables
%    iArtifStab   integer flag to invoke artificial stabilization
%                 = 0: No artificial stabilization
%                 > 0: Artificial stabilization (needs definition of StabMat)
%    StabMat      artificial stabilization matrix; (Nx,Ny); nonzero only for iArtifStab>0           
%

% Constants
d2r = pi/180;
r2d = 180/pi;

%----------------------------------------------------------------------------------------
% Model definition
state_eq   = 'xdot_TC11_lon_sp';         % function for state equations                
obser_eq   = 'obs_TC11_lon_sp';          % function for observation equations
Ny         = 2;                          % Number of system states
Nx         = 2;                          % Number of observation variables
Nu         = 1;                          % Number of input (control) variables
NparSys    = 8;                          % number of system parameters
Nparam     = NparSys;                    % Total number of system and bias parameters
dt         = 0.04;                       % sampling time
iArtifStab = 0;                          % No artificial stabilization

disp(['Test Case = ', num2str(test_case)]);
disp('Short period motion, nx=2, ny=2, nu=1, ATTAS')

%----------------------------------------------------------------------------------------
% Load flight data for Nzi time segments to be analyzed and concatenate 
load ..\flt_data\fAttasElv1;  
load ..\flt_data\fAttasElv2;  
Nzi  = 2;
data = [fAttasElv1; fAttasElv2]; 

% Number of data points
Ndata1 = size(fAttasElv1,1);
Ndata2 = size(fAttasElv1,1);
izhf   = [Ndata1; Ndata1+Ndata2];
Ndata  = size(data,1);

% Generate new time axis
t = [0:dt:Ndata*dt-dt]';

% Observation variables angle of attack and pitch rate (alpha, q)
Z    = [data(:,13)*d2r data(:,8)*d2r];
   
% Input variable elevator deflection de
Uinp = [data(:,22)*d2r];

% Initial starting values for unknown parameters (aerodynamic derivatives) 
param = [-2.52504e-03; -2.13832e-01;  2.78189e-02;  1.66147e-01;...
          2.71618e-01; -2.73646e+00; -1.08034e+00; -3.18940e+00];

% Flag for free and fixed parameters
%parFlag = ones(Nparam,1);
parFlag = [1;  1;  1;  1;...
           1;  1;  1;  1];

% Total number of free parameters
NparID = size(find(parFlag~=0),1); 

% Initial conditions alpha0, q0 -- x0(n,Nzi)
x0(:,1) = [Z(1,1); Z(1,2)];           % first time segment
x0(:,2) = [Z(1,1); Z(1,2)];           % second time segment

% Artificial stabilization matrix
StabMat = zeros(Nx,Ny);