Conversion to double from function_handle is not possible.

Question

hussain askar 2021-10-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1565546-conversion-to-double-from-function_handle-is-not-possible

编辑： Stephen23 2021-10-17

I'm trying to solve an economic dispatch problem using the fmincon function, but i'm getting many different errors in the function inside the loop. Can you please help me run this code without errors? This is my first time using fmincon.

Nc = 3;
a = [ 0.06 0.03 0.04];
b = [ 0.5 0.25 0.3];
c = [ 5 4 2 ];
p0 = [2 4 7 ];
objective = zeros(1,3);
for i = 1:Nc
    objective(i) = @(p) a(i)^2 * p(i)^2 + b(i) * p(i) + c(i);
end
pd = 550;
A = [];
b = [];
Aeq = [ p(1) p(2) p(3)];
beq = [ pd ];
lb = [ 0 0 0 ];
ub = [ 4 6 9 ];
% disp([' Initial Objectives: ' num2str(objective(p0))])    
cc = fmincon(objective(i), p0, A , b , Aeq, beq, lb, ub);
disp(cc)

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Answer 1

Jan 2021-10-17

1
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https://ww2.mathworks.cn/matlabcentral/answers/1565546-conversion-to-double-from-function_handle-is-not-possible#answer_810291

在 MATLAB Online 中打开

objective = zeros(1,3);  % Here objective is a double
for i = 1:Nc
    % And here you want to store a function handle in the double elements:
    objective(i) = @(p) a(i)^2 * p(i)^2 + b(i) * p(i) + c(i);
end

This cannot work.

Try this instead:

objective = @(p) a.^2 .* p.^2 + b .* p + c;

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Stephen23 2021-10-17

编辑：Stephen23 2021-10-17

The objective function for FMINCON needs to return a scalar, so the anonymous function will need to use SUM, MEAN, or some other way to return a single value as the output.

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