Failure in initial nonlinear constraint function evaluation. FMINCON cannot continue.

Hello I am really new both with matlab and optimization problems, but I have been several hours trying to fix this and I am really lost.

I get that answer with every code i tried, I really would appreciate any help.

******The extra file I created for the non linear constrain has this:

function [ineq_cons,eq_cons]= constraint_Ejercicio20(x)

ineq_cons =[(x(1)^2 + (x(2)^2 - 4];

eq_cons =[];

*******The main code is this:

fun_max = @(x) - x(1) * (x(2));

A = [-1,-2;

-1,0;

0,-1];

b = [-2, 0, 0];

Aeq = [];

beq = [];

cons = @constraint_Ejercicio20;

lb = [];

ub = [];

> x0 = [0;

0];

[x_max,fval_max,exitflag,output,lambda_max] = fmincon(fun_max,x0,A,b,Aeq,beq,lb,ub,cons);

*********And the problem i need to solve is this

% Opt: q(x,y)= x*y

% S.t.

% x^2+y^2 <= 4

% x+2y >= 2

% x >= 0

% y >= 0

Thanks in advace

Answer 1

[Alan Weiss]

You did a good job converting the problem to code. Your only real errors are typos in the nonlinear constraint function. Try this:

function  [ineq_cons,eq_cons]= constraint_Ejercicio20(x)
ineq_cons = x(1)^2 + x(2)^2 - 4;
eq_cons = [];
end

Let me also say that your linear constraints, while correct, should only have one row in A and one entry in b. The second and third rows are better expressed as lower bounds, lb.

Alan Weiss

MATLAB mathematical toolbox documentation