fmincon implementing nonlinear constraints

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Reed
Reed 2022-7-5
编辑： Torsten 2022-7-6
I am trying to fit my objective function (ogden_funct) to the following constraints and am running into errors.
For constraint 1) I get an error of 'Error using fmincon
Supplied objective function must return a scalar value'
For constraint 2) I am not sure where/how to implement this.
My ideal solution will implement constraint 1) and 2)
Any ideas help.
%objective
ogden_funct = @(c) c(1)*(xdata.^(c(4)-1)-xdata.^((-1)/2*c(4)-1)) + ...
c(2)*(xdata.^(c(5)-1)-xdata.^(-1/2*c(5)-1)) + ...
c(3)*(xdata.^(c(6)-1)-xdata.^((-1)/2*c(6)-1))- ydata;
% Constraint 1)
c(1)*c(4) + c(2)*c(5) + c(3)*c(6) = 2;
% my attempt, writing a function nlcon(c) in a new file
function [z, zeq] = nlcon(c)
z = 2 - (c(1)*c(4) + c(2)*c(5) + c(3)*c(6));
zeq = [];
end
% then calling fmincon
x = fmincon(ogden_funct, Initial_Guess,A,b,Aeq,beq,[],[],nonlincon); % Where Initial_Guess...[] in this case dont matter
% Constraint 2)
c(1)*c(4)>0; c(2)*c(5)>0; c(3)*c(6)>0; % no ideas on how to implement this
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Matt J
Matt J 2022-7-6
编辑：Matt J 2022-7-6
Objective for fmincon must be ogden_funct = @(c) sum(c(1)*(xdata.^(c(4)-1)....).^2;
mean() would be better:
ogden_funct = @(c) mean(c(1)*(xdata.^(c(4)-1)-xdata.^((-1)/2*c(4)-1)) + ...
c(2)*(xdata.^(c(5)-1)-xdata.^(-1/2*c(5)-1)) + ...
c(3)*(xdata.^(c(6)-1)-xdata.^((-1)/2*c(6)-1))- ydata).^2;
That way, your optimoptions needn't depend so much on the size of xdata.
Torsten
Torsten 2022-7-6
编辑：Torsten 2022-7-6
@Reed
Could you describe to me, in the function script, what the z = [.....] is achieving?
It's an attempt to implement your constraints
-c(1)*c(4) <= 0
-c(2)*c(5) <= 0
-c(3)*c(6) <= 0

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