Why is it Showing this error? Help me please.

This is the coding:

cl=load("clnaca0018.mat","cl");
cd=load("cdnaca0018.mat","cd");
% Objective function for power coefficient optimization
objectiveFunction = @(x)((cl)*cosd(x(2))+((cd)*sind(x(2)))*x(1));
% Initial guess
x0 = [10, 4];
% lower&upper bounds
lb = [0, 2];
ub = [15, 8];
A=[];
b=[];
Aeq=[];
beq=[];
% Perform optimization
x = fmincon(objectiveFunction,x0,A,b,Aeq,beq,lb,ub);
% Extract optimized parameters
optimizedTSR = x(1);
optimizedtwistAngle = x(2:end);
% Display the optimized parameters
disp('Optimized Parameters:');
disp(['Optimized Tip-Speed Ratio: ', num2str(x(1))]);
disp(['Optimized Blade Twist Angle: ', num2str(x(2))]);

This is the error:

Operator '*' is not supported for operands of type 'struct'.

Error in code1>@(x)((cl)*cosd(x(2))+((cd)*sind(x(2)))*x(1)) (line 5)

objectiveFunction = @(x)((cl)*cosd(x(2))+((cd)*sind(x(2)))*x(1));

Error in fmincon (line 563)

initVals.f = feval(funfcn{3},X,varargin{:});

Error in code1 (line 19)

x = fmincon(objectiveFunction,x0,A,b,Aeq,beq,lb,ub);

Answer 1

[Walter Roberson]

Change

cl=load("clnaca0018.mat","cl");
cd=load("cdnaca0018.mat","cd");

to

cl=load("clnaca0018.mat","cl");
cd=load("cdnaca0018.mat","cd");
cl = cl.cl;
cd = cd.cd;

[salman]

this error shown

Error using fmincon

Supplied objective function must return a scalar value.

Error in code1 (line 20)

x = fmincon(objectiveFunction,x0,A,b,Aeq,beq,lb,ub);

[Walter Roberson]

That is to be expected if either you cl or your cd are non-scalar.

You could try

objectiveFunction = @(x)sum(((cl)*cosd(x(2))+((cd)*sind(x(2)))*x(1)).^2);