Question about writing if statement on function nlcon()

function [c, ceq] = nlcon(x)
c = [];
Pi_ss_nl = 1.005;
beta_d = 0.9963;
beta_l = 0.9901;
i_l_ss_nl = Pi_ss_nl/beta_l - 1;
i_d_ss_nl =  Pi_ss_nl/beta_d - 1;
i_r_ss_nl = i_d_ss_nl;
iota = 0.88;
nu = 6;
gamma = 0.0001;
R_bar = 0.07;
m_bar = 0.01;

% if x(2) < R_bar || x(3) < m_bar
%     ceq = x(4) - ((i_l_ss_nl - i_d_ss_nl)/(1+i_d_ss_nl))*x(1) + ((i_d_ss_nl - i_r_ss_nl)/(1+i_d_ss_nl))*x(2) +...
%     ((i_d_ss_nl + gamma)/(1+i_d_ss_nl))*x(3) + (x(1)^nu)*(x(4)^-iota) + 1/2*(x(2) - R_bar)^2 + 1/2*(x(3) - m_bar)^2;
% elseif x(2) >= R_bar || x(3) < m_bar
%     ceq = x(4) - ((i_l_ss_nl - i_d_ss_nl)/(1+i_d_ss_nl))*x(1) + ((i_d_ss_nl - i_r_ss_nl)/(1+i_d_ss_nl))*x(2) +...
%     ((i_d_ss_nl + gamma)/(1+i_d_ss_nl))*x(3) + (x(1)^nu)*(x(4)^-iota) + 1/2*(x(3) - m_bar)^2;
% elseif x(2) < R_bar || x(3) >= m_bar
%     ceq = x(4) - ((i_l_ss_nl - i_d_ss_nl)/(1+i_d_ss_nl))*x(1) + ((i_d_ss_nl - i_r_ss_nl)/(1+i_d_ss_nl))*x(2) +...
%     ((i_d_ss_nl + gamma)/(1+i_d_ss_nl))*x(3) + (x(1)^nu)*(x(4)^-iota) + 1/2*(x(2) - R_bar)^2;
% elseif x(2) >= R_bar || x(3) >= m_bar 
%     ceq = x(4) - ((i_l_ss_nl - i_d_ss_nl)/(1+i_d_ss_nl))*x(1) + ((i_d_ss_nl - i_r_ss_nl)/(1+i_d_ss_nl))*x(2) +...
%     ((i_d_ss_nl + gamma)/(1+i_d_ss_nl))*x(3) + (x(1)^nu)*(x(4)^-iota);
% end
end

What I want is ceq to be different for 4 scenarios.

Is there a way I can do this?

How do I write if statement on nlcon()?

Any help would really be appreciated!

Answer 1

[Anmol Dhiman]

Hi Hyunmin,

In my opinion the problem with the above if conditions is the fact that you are using OR(||) instead of AND(&&) in the condition of the if statement.

for eg, A||B is true if any of A , B is true. In your case, both the statements will come as true if "x(3) < m_bar" is statisfied. Hence the first if condtion is nver executed.

x(2) < R_bar || x(3) < m_bar
x(2) >= R_bar || x(3) < m_bar

Try using && instead of ||.

Hope it Helps