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

조회 수: 2(최근 30일)
Yoon Ho Roh
Yoon Ho Roh 2021년 6월 9일
답변: Shadaab Siddiqie 2021년 6월 15일
I cannot run fmincon because of the error 'barrier, Nonlinear constraint function is undefined at initial point. Fmincon cannot continue.'
Thanks in advance.
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

답변(1개)

Shadaab Siddiqie
Shadaab Siddiqie 2021년 6월 15일
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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