# Nonlinear constraint function is undefined at initial point. Fmincon cannot continue.

52 vues (au cours des 30 derniers jours)
Yoon Ho Roh le 9 Juin 2021
I cannot run fmincon because of the error 'barrier, Nonlinear constraint function is undefined at initial point. Fmincon cannot continue.'
Here is my code
Main fmincon function
R = 25;
H = 27;
LB = [2 * R / H + 2 / H, 0.4, 0.4, 0.4, 0.4];
UB = [4 * R / H - 2 / H, 2.5, 2.5, 2.5, 2.5];
x0 = [1, 1, 1, 1, 1];
tol = 1.0e-6;
options = optimset('display', 'iter', 'PlotFcns', 'optimplotfval', 'TolX', tol, 'TolFun', tol, 'TolCon', tol, 'Algorithm', 'interior-point')
[x, fval, exitflag, output] = fmincon(@(x) objective(x,H), x0, [], [], [], [], LB, UB, @(x) constraints(x,H,R), options)
Objective function
function f = objective (x, H)
f = H^2 * (x(1) + x(2)) * (x(3) + 2 * x(4) + x(1));
end
Constraints
function [C, Ceq] = constraints (x, H, R)
C(2) = x(5) - 2 * R / H + 2 / H;
C(3) = x(3) - 4 * R / H + 2 / H;
C(4) = x(2) - 4 * R / H + 2 / H;
C(5) = 5 - 2 * atan (0.5*(x(3) - x(5)) / x(2));
C(1) = x(2)*((467208*x(2)*x(5)^3*x(3) + 152286*x(2)*x(5)^3 - 1401624*x(2)*x(5)^2*x(3)^2 - 456858*x(2)*x(5)^2*x(3) + 1401624*x(2)*x(5)*x(3)^3 + 456858*x(2)*x(5)*x(3)^2 - 467208*x(2)*x(3)^4 - 152286*x(2)*x(3)^3)/(625*x(2)*x(5)^3 - 1875*x(2)*x(5)^2*x(3) + 1875*x(2)*x(5)*x(3)^2 - 625*x(2)*x(3)^3) - ((1875*x(2)^2*x(5)^2*x(3) - 3750*x(2)^2*x(5)*x(3)^2 + 1875*x(2)^2*x(3)^3)*(116802*x(5)^4 - 467208*x(5)^3*x(3) + 700812*x(5)^2*x(3)^2 - 467208*x(5)*x(3)^3 + 116802*x(3)^4))/(625*x(2)*x(5)^3 - 1875*x(2)*x(5)^2*x(3) + 1875*x(2)*x(5)*x(3)^2 - 625*x(2)*x(3)^3)^2) - ((6*(6447*x(2)^3*x(3) + 5000*x(2)^3))/(x(5) - x(3)) + 38682*x(2)^2*x(2))/(625*x(2)^2*x(3)^2 - x(2)*(1250*x(2)*x(3)^2 - 1250*x(2)*x(5)*x(3)) + x(2)^2*(625*x(5)^2 - 1250*x(5)*x(3) + 625*x(3)^2)) + (14166*x(2)*log(- x(2)*x(3) - x(2)*(x(5) - x(3))))/(625*x(5) - 625*x(3)) + (x(2)^2*(116802*x(5)^4 - 467208*x(5)^3*x(3) + 700812*x(5)^2*x(3)^2 - 467208*x(5)*x(3)^3 + 116802*x(3)^4))/(2*(625*x(2)*x(5)^3 - 1875*x(2)*x(5)^2*x(3) + 1875*x(2)*x(5)*x(3)^2 - 625*x(2)*x(3)^3)) - 96 * ((1 - 1.3553 * x(1) + 1.9467 * x(1)^2) * (x(1) + 1)^2 * ((x(3) + 2 * x(4) + x(1) + x(2)) / H))/ x(1)^3
Ceq = [];
end
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### Réponses (1)

Shadaab Siddiqie le 15 Juin 2021
From my understanding you are getting an error "Nonlinear constraint function is undefined at initial point". This might be because your function is not defined a the initial point x0 (in your case [1,1,1,1,1]). You can either change your initial value or may be recheck your objective and its constraints again.
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