Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parenthe

fun = @(x) (0.00 0.00 0.01 -0.01 -0.01 -0.05 0.12 0.16 0.20 0.05 -0.02 0.11 0.06 0.04 -0.08 0.43 -0.26 -0.18 -0.12 -0.12);

x0 = [21.70 2.40 7.60 22.80 30.00 5.80 11.20 6.20 8.20 3.50 9.00 3.20 9.50 2.20 17.50 3.20 8.70 3.50 2.40 10.60];

A = [];

b = [];

Li = [21.70 2.40 7.60 22.80 30.00 5.80 11.20 6.20 8.20 3.50 9.00 3.20 9.50 2.20 17.50 3.20 8.70 3.50 2.40 10.60];

Aeq = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1];

beq = 0;

lb = -0.1*Li;

ub = 0.1*Li;

[x fval] = fmincon(fun,x0,A,b,Aeq,beq,lb,ub)

Answer 1

[VBBV]

fun = @(x) [0.00	0.00	0.01	-0.01	-0.01	-0.05	0.12	0.16	0.20	0.05	-0.02	0.11	0.06	0.04	-0.08	0.43	-0.26	-0.18	-0.12	-0.12]; 
          %^^ use []  

use ' [ ' insead of ' ( '

[akash]

HI VBBV when i use '[]' instead of '()' i am getting following error.

Error using fmincon

Supplied objective function must return a scalar value.

Error in test_case30 (line 13)

[x fval] = fmincon(fun,x0,A,b,Aeq,beq,lb,ub)

[Stephen23]

"Error using fmincon, Supplied objective function must return a scalar value."

See: https://www.mathworks.com/matlabcentral/answers/1874017-invalid-expression-check-for-missing-multiplication-operator-missing-or-unbalanced-delimiters-or#answer_1123342

[VBBV]

Hi akash,

K = [0.00  0.00  0.01  -0.01  -0.01  -0.05  0.12  0.16  0.20  0.05  -0.02  0.11  0.06  0.04  -0.08  0.43  -0.26  -0.18  -0.12  -0.12]; 
[x fval] = fmincon(@fun,x0,A,b,Aeq,beq,lb,ub)
function x = fun(K)
% do something here 
% return x as scalar 
end

The function defined has no variables except the vector. Instead define a function and call it with function handle as argument shown above, passing the vector

Answer 2

[Steven Lord]

This is not valid MATLAB syntax. I've commented it out so that later lines of code in this answer can run.

% fun = @(x) (0.00	0.00	0.01	-0.01	-0.01	-0.05	0.12	0.16	0.20	0.05	-0.02	0.11	0.06	0.04	-0.08	0.43	-0.26	-0.18	-0.12	-0.12); 

If you wanted fun to be a function handle that returns that specific vector use [] to create the vector.

fun = @(x) [0.00	0.00	0.01	-0.01	-0.01	-0.05	0.12	0.16	0.20	0.05	-0.02	0.11	0.06	0.04	-0.08	0.43	-0.26	-0.18	-0.12	-0.12];
fun(42)

ans = 1×20

0 0 0.0100 -0.0100 -0.0100 -0.0500 0.1200 0.1600 0.2000 0.0500 -0.0200 0.1100 0.0600 0.0400 -0.0800 0.4300 -0.2600 -0.1800 -0.1200 -0.1200

But that function is not going to satisfy the requirements fmincon imposes on the function you pass into it. Without knowing what problem you're trying to solve it's going to be impossible to say how to modify your fun function to solve it.

[akash]

Hi steven,

I am trying to minimize the objective function. The objective function is

max ( x1 * 0.00 + x2* 0.00 + x3*0.01 ------------------x20*(-0.12) )

the values of x are [21.70 2.40 7.60 22.80 30.00 5.80 11.20 6.20 8.20 3.50 9.00 3.20 9.50 2.20 17.50 3.20 8.70 3.50 2.40 10.60]

the limit for x is -0.1*Li to +0.1Li

[Alan Weiss]

I'm not sure that I understand you, but your objective function might be best coded as

fun = dot(x,Li)

But I am not sure exactly what you are doing. Is it linear programming? If so, see the linprog documentation.

Alan Weiss

MATLAB mathematical toolbox documentation