optimization function fmincon with a transfer function

2015 11 8
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更新时间：2015 11 12
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Dear Sir, How can i use the optimization function "fmincon" or any other if the optimization function is a transfer function and also the constraints are dependent up on a transfer functions also. Thank you

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Alan Weiss
Alan Weiss 2015-11-9

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You have to be able to evaluate the objective function for fmincon to work. So, how do you evaluate a transfer function as a function of the optimization parameters? Answer that, and you'll be able to use fmincon.
Alan Weiss
MATLAB mathematical toolbox documentation

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ashraf abdulhamed
ashraf abdulhamed 2015-11-10
I'd like to show you my problem in details and the error message i get may you can help me
the objective function is:
function f=qfunction(x) f=tf([x(1) x(2)],[1 1340 448900]);
the constraints
function [c,ceq]=constraints(x) T_con_num=[44296000*x(1)+1.894e+11 44296000*x(2)+3.8556e+14 2.6159e+17 5.915e+19]; T_con_den=[1 1.784e+4 1.6099e+8 3.8231e+11 4.477e+14 2.6159e+17 5.915e+19]; W2_num=[1 1.784e+4 1.6099e+8 1.9291e+11-44296000*x(1) 6.2144e+13-44296000*x(2)-3.7363e-6*x(1) 7.4476e-5*x(1)-3.7363e-6*x(2)+4.9173 7.4476e-5*x(2)-104.484]; W2_den=[1 1.783956e+4 1.6099e+8 3.82308e+11 4.477e+14 2.61587e+17 5.9149777e+19]; W2=tf(W2_num,W2_den); t=0:0.001:0.1; y1_d=0.5*step(W2_num,W2_den,t); y2_d_num=34.558*W2_num; y2_d_den=conv([1 0 4.7769e+5],W2_den); y2_d=impulse(y2_d_num,y2_d_den,t); y3_d_num=conv([0.1 0],W2_num); y3_d_den=conv([1 0 1.1942e+5],W2_den); y3_d=impulse(y3_d_num,y3_d_den,t); y_d=y1_d+y2_d+y3_d; ypk=step(T_con_num,T_con_den,t); y_tot=ypk+y_d; c=[max(ypk)-1.2; norm(W2,inf)-1.3; max(y_tot)-1.1]; ceq=[];
The optimization file
x0=[1;1]; options=optimoptions(@fmincon,'Algorithm','sqp'); [x,fval,exitflag,output]=fmincon(@qfunction,x0,[],[],[],[],[],[],@constraints,options);
The error message is:
Error using fmincon (line 788) FMINCON requires all values returned by user functions to be of data type double.
Error in optimization (line 3) [x,fval,exitflag,output]=fmincon(@qfunction,x0,[],[],[],[],[],[],@constraints,options);
Alan Weiss
Alan Weiss 2015-11-10
Please mark your code with the {} Code button so we have a chance of reading it.
Alan Weiss
MATLAB mathematical toolbox documentation
ashraf abdulhamed
ashraf abdulhamed 2015-11-12
Dear Alan Weiss thank you for your interest in replying my question, please find the attached MATLAB m files for my problem. I hope if you can help me. Thank you

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