Why am I getting Undefined function or variable 'kp' despite having defined it in the code?

function dAdT = polyadiabatic(T,A)
dAdT = zeros(2,1);

% Kinetics
Rp = (kp).*rho.*A(1).*((2.*ki.*((rho.*A(1).^3)))./ktc).^0.5;

% Formulae
ki = 2.019.*10.*exp(-13810./A(2)); % m6/kg.s
kp = 1.009.*(10.^5).*exp(-3557./A(2)); % m3/kg.s
%kp = 100900;
ktc = 2.205.*(10.^7).*exp(-844./A(2)).*exp(-2.*((A1.*wp)+(A2.*(wp.^2))+(A3.*(wp.^3)))); % m3/kg.s
A1 = 2.57-((5.05.*0.001).*A(2));
A2 = 9.56-((1.76.*0.01).*A(2));
A3 = -3.032+((7.85.*0.001).*A(2));
rho = 845-(A(2)-353)+((200+(A(2)-353)).*wp); % kg/m3
wp = 1-A(1);

% Parameters
deltaH = -6.7.*(10.^5); % J/kg
cp = 1.884.*1000; % J/kg.K

% Mass balance
dAdT(1) = -(Rp./rho);

% Energy balance
dAdT(2) = -(Rp.*deltaH)./(cp.*rho);

end

To call the function:

function [T,A] = call_polyadiabatic()

tspan = [0 40000];

% Initial conditions
A1_0 = 1;
A2_0 = 360;

[T,A] = ode45(@polyadiabatic,tspan,[A1_0 A2_0]);
End

Error:

call_polyadiabatic
Undefined function or variable 'kp'.

Error in polyadiabatic (line 5)
Rp = (kp).*rho.*A(1).*((2.*ki.*((rho.*A(1).^3)))./ktc).^0.5;

Error in odearguments (line 90)
f0 = feval(ode,t0,y0,args{:});   % ODE15I sets args{1} to yp0.

Error in ode45 (line 115)
    odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Error in call_polyadiabatic (line 9)
[T,A] = ode45(@polyadiabatic,tspan,[A1_0 A2_0]);

Answer 1

[Aquatris]

Becuase you define "kp" variable a little late. From your polyadiabatic function;

% Kinetics
Rp = (kp).*rho.*A(1).*((2.*ki.*((rho.*A(1).^3)))./ktc).^0.5; % THIS REQUIRES kp VARIABLE
% Formulae
ki = 2.019.*10.*exp(-13810./A(2)); % m6/kg.s                 % HERE IS WHERE YOU DEFINE kp VARIABLE
kp = 1.009.*(10.^5).*exp(-3557./A(2)); % m3/kg.s

You will get a similar error for A1, A2, A3, and wp variables as well. Put them in the beginning of the function, before you use them.

[StillANovice]

You are a star, thank you!