idnlgrey fixed step problem

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erhan aksu 2016-1-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/263036-idnlgrey-fixed-step-problem

 function [dx, y] = examp2(t, x, u,a,b,c,d, varargin)
   % Output equations.
  y = [x(1);                         ... % 
       x(2)                          ... % 
      ];
   % State equations.
  dx = [a*x(1)+b*x(2);                   ... %
        c*x(1)+d*x(2);                   ... % 
       ];

Main Programme clear all clc dataall=xlsread('data.xlsx'); t=dataall(:,1); d1=dataall(:,2); d2=dataall(:,3); y=[d1 d2]; data = iddata(y, [], 0.01, 'Name', 'B'); % FileName = 'examp2'; % File describing the model structure. % Order = [2 0 2]; % Model orders [ny nu nx]. % InitialStates = [9; -1]; % Initial initial states. % Ts = 0; % Time-continuous system. % % a=-1; b=6; c=2; d=1; % Parameters = {a,b,c,d}; % nonlinear_model = idnlgrey(FileName, Order, Parameters, InitialStates, Ts); % nonlinear_model.Algorithm.SimulationOptions.Solver = 'ode1'; % Euler forward. % nonlinear_model.Algorithm.SimulationOptions.FixedStep = (????); % Step size. % nonlinear_model = pem(data,nonlinear_model); % compare(data,nonlinear_model)

This main programme is used to estimate a,b,c,d parameter. Main dif.equaition is x'=-2*x+7*y and y'=3*x+2*y . I used grey box model. When I used ode45 programme is working. But When I used ode1 this is fixed step model my final value is zero. Why? How can I do fixed step size value correctly.(0.01 value tried but it is not working?) Good days