Solve a multiobjective optimization problem by problem-based approach in Matlab2021a

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Ulisses Anastácio de Oliveira
编辑： Torsten 2023-1-16
I am trying this:
% teste_multiobjective file
x1 = optimvar('x1','LowerBound',0);
x2 = optimvar('x2','LowerBound',0);
s1 = 5*x1 + 2.5*x2 >= 5;
s2 = x1 + x2 <= 5;
s3 = 2*x1 + 2*x2 >= 3;
% s4 = 20*x1 + 10 * x2 == 20;
% s5 = 60*x1+90*x2 == 90;
prob = optimproblem('ObjectiveSense','minimize');
prob.Objective.obj1 = 20*x1 + 10*x2;
prob.Objective.obj2 = 60*x1 + 90*x2;
prob.Constraints.s1 = s1;
prob.Constraints.s2 = s2;
prob.Constraints.s3 = s3;
% prob.Constraints.s4 = s4;
% prob.Constraints.s5 = s5;
options = optimoptions('gamultiobj',HybridFcn="fgoalattain");
[sol,fval,exitflag,output] = solve(prob,Options=options);
disp(sol.x1)
disp(sol.x2)
disp(fval)
And matlab 2021a show me this:
Error using test_multiobjective
(line 16)
Objective must be a scalar
OptimizationExpression or a
struct containing a scalar
OptimizationExpression.
Does anyone help me, please?

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采纳的回答

Matt J
Matt J 2023-1-16
编辑：Matt J 2023-1-16
You can use prob2matrices from this FEX download,
https://www.mathworks.com/matlabcentral/fileexchange/74481-prob2matrices-a-selective-version-of-prob2struct?s_tid=srchtitle
% teste_multiobjective file
x1 = optimvar('x1','LowerBound',0);
x2 = optimvar('x2','LowerBound',0);
con.s1 = 5*x1 + 2.5*x2 >= 5;
con.s2 = x1 + x2 <= 5;
con.s3 = 2*x1 + 2*x2 >= 3;
options = optimoptions('gamultiobj',HybridFcn="fgoalattain");
p=prob2matrices({x1,x2},'Constraints', con);
fitnessfcn = @(x)[20*x(1) + 10*x(2),60*x(1) + 90*x(2)];
x = gamultiobj(fitnessfcn,2,p.A,p.b,p.Aeq,p.beq,p.lb,p.ub,[],p.intcon,options)

更多回答（2 个）

Sulaymon Eshkabilov
Ran in:
It is working ok:
% teste_multiobjective file
x1 = optimvar('x1','LowerBound',0);
x2 = optimvar('x2','LowerBound',0);
s1 = 5*x1 + 2.5*x2 >= 5;
s2 = x1 + x2 <= 5;
s3 = 2*x1 + 2*x2 >= 3;
% s4 = 20*x1 + 10 * x2 == 20;
% s5 = 60*x1+90*x2 == 90;
prob = optimproblem('ObjectiveSense','minimize');
prob.Objective.obj1 = 20*x1 + 10*x2;
prob.Objective.obj2 = 60*x1 + 90*x2;
prob.Constraints.s1 = s1;
prob.Constraints.s2 = s2;
prob.Constraints.s3 = s3;
% prob.Constraints.s4 = s4;
% prob.Constraints.s5 = s5;
options = optimoptions('gamultiobj',HybridFcn="fgoalattain");
[sol,fval,exitflag,output] = solve(prob,Options=options);
Solving problem using gamultiobj. Optimization terminated: average change in the spread of Pareto solutions less than options.FunctionTolerance.
disp(sol.x1)
0.5000 0.9286 0.8427 0.6718 0.6207 0.5535 0.7163 1.2131 0.8641 1.4535 1.4535 1.1060 0.7336 0.7946 1.1636 1.0476 0.9609 1.2796
disp(sol.x2)
0.9995 0.5717 0.6682 0.8312 0.8812 0.9501 0.7895 0.2899 0.6376 0.0476 0.0476 0.3940 0.7664 0.7054 0.3364 0.4524 0.5391 0.2204
disp(fval)
19.9961 24.2890 23.5362 21.7473 21.2265 20.5704 22.2210 27.1606 23.6579 29.5454 29.5454 26.0605 22.3359 22.9464 26.6358 25.4756 24.6093 27.7957 119.9594 107.1712 110.6984 115.1156 116.5505 118.7150 114.0360 98.8739 109.2299 91.4904 91.4904 101.8185 112.9924 111.1607 100.0927 103.5733 106.1721 96.6128
  2 个评论
Ulisses Anastácio de Oliveira
Ulisses Anastácio de Oliveira 2023-1-15
Thanks!! You ran this in matlab 2022b, right? I am using matlab 2021a. Do you know if there is other way to write the code to fit it in matlab 2021a?
Torsten
Torsten 2023-1-15
编辑：Torsten 2023-1-16
Ran in:
A = [-5 -2.5 ;1 1 ;-2 -2 ];
b = [-5;5;-3];
lb = [0; 0];
fitnessfcn = @(x)[20*x(1) + 10*x(2),60*x(1) + 90*x(2)];
x = gamultiobj(fitnessfcn,2,A,b,[],[],lb,[]);
Optimization terminated: average change in the spread of Pareto solutions less than options.FunctionTolerance.
[x1,I] = sort(x(:,1));
x2 = x(I,2);
plot(x1,x2)

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Torsten
Torsten 2023-1-15
Ran in:
% teste_multiobjective file
x1 = optimvar('x1','LowerBound',0);
x2 = optimvar('x2','LowerBound',0);
s1 = 5*x1 + 2.5*x2 >= 5;
s2 = x1 + x2 <= 5;
s3 = 2*x1 + 2*x2 >= 3;
% s4 = 20*x1 + 10 * x2 == 20;
% s5 = 60*x1+90*x2 == 90;
prob = optimproblem('ObjectiveSense','minimize');
prob.Objective.obj1 = 20*x1 + 10*x2;
prob.Objective.obj2 = 60*x1 + 90*x2;
prob.Constraints.s1 = s1;
prob.Constraints.s2 = s2;
prob.Constraints.s3 = s3;
% prob.Constraints.s4 = s4;
% prob.Constraints.s5 = s5;
options = optimoptions('gamultiobj',HybridFcn="fgoalattain");
[sol,fval,exitflag,output] = solve(prob,Options=options);
Solving problem using gamultiobj. Optimization terminated: average change in the spread of Pareto solutions less than options.FunctionTolerance.
[x1,I] = sort(sol.x1);
x2 = sol.x2;
x2 = x2(I);
plot(x1,x2)

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