ERROR: "Undefined function or method for double type" + "feval error" - Strange case/no plots

Greetings,

My script only plots 1 out of 3 equations. It returns an error that stops the other two:

??? Error using ==> feval Undefined function or method 'F_CubeSat_AerotechG80' for input arguments of type 'double'.

Error in ==> odearguments at 98 f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ==> ode15s at 227 [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

Error in ==> F__CubeSat_rocket1 at 46 [t y] = ode15s('F__CubeSat_AerotechG80',t,yo); % Instruccion para utilizar _

This is the code for the main script

%-----------------------------Rocket1--------------------------------
% Este programa calcula la trayectoria vertical de un cohete.
% Considera efectos de fuerza de arrastre y de empuje.  Se presume
% que el vuelo es perfectamente vertical y no hay velocidad de viento.
% La densidad del aire y la aceleracion de la gravedad se presumen
% constantes
%--------------------------29/01/2013---------------------------------
clc
clear all
close all

global T rho Cd Af g mo mdot tb tf dt Dt

load(('F__CubeSat_AerotechG80.txt')) %Descarga el empuje del motor

[nr nc] = size(F__CubeSat_AerotechG80);
n = nr*nc;                %Cantidad total de datos en archivo del motor
tf = 0.03125*(n-1);       %Tiempo final de vuelo
Dt = 0.03125;             %Incremento de tiempo original datos del motor
tt = (0:Dt:tf);  
T = F__CubeSat_AerotechG80';
dt = 0.001;               %Incremento de tiempo deseado para solucion
t = (0:dt:tf);
[Nr Nc] = size(t);

%--------------------Grafico fuerza de empuje--------------------------

figure;
plot(tt,T); grid on;
xlabel('tiempo [seg]');
ylabel('Empuje [N]');

%------------------------------Datos-----------------------------------

rho = 1.2041;   % Densidad del aire [kg/m^3]
Cd = 0.2;       % Coeficiente de arrastre
Af = 2.026e-3;  % Area frontal del cohete [m^2]
g = 9.81;       % Aceleracion gravedad [m/s^2]
mo = 0.5;       % Masa inicial del cohete [kg]
tb = 1.5;       % Tiempo de combustion del motor [seg]
mdot = 0.0417;  % Flujo masico de combustible[kg/s]
yo = [0;0];     % Condiciones iniciales [posicion y velocidad]

%--------------------------Computo de posicion--------------------------

[t y] = ode15s('F__CubeSat_AerotechG80',t,yo);  % Instruccion para utilizar 
% la libreria de ecuaciones diferenciales

%----------------------Grafico de posicion vs tiempo--------------------

figure;
plot(t,y(:,1)); grid on;
xlabel('Tiempo [seg]');
ylabel('Altura [m]');

%---------------------Grafico de velocidad vs tiempo--------------------

figure;
plot(t,y(:,2)); grid on;
xlabel('Tiempo [seg]');
ylabel('Velocidad [m]');

%---------------Computo y grafico de aceleracion vs tiempo--------------

deltav = diff(y(:,2));
deltat = diff(t);
a = deltav./deltat;
figure;
plot (t(1:Nc-1),a); grid on;
xlabel('Tiempo [seg]');
ylabel('Aceleracion [m/s^2]');

This is the code for the supporting script file:

function ydot=F__CubeSat_rocket(t,y)
global T rho Cd Af g mo mdot tb tf dt Dt
dt = 0.001;
if t<=tb
   m = mo-mdot*t;
else
   m = mo-mdot*tb;
end
ty = (0:Dt:tf);
Tb = interp1(ty,T,t);
ydot=[y(2);((Tb-0.5*rho*Cd*Af*y(2)^2)/m)-g];

I have no idea how to resolve it. It should be working; I've even thought it's a MatLab version issue. I will thank you from the bottom of my heart if you can explain to me what the error here is.

All thanks in advance.

-Moya

[per isakson]

"[...]Undefined function or method 'F_CubeSat_AerotechG80"_. What does

     which F__CubeSat_AerotechG80

return?

[E Moya]

It returns:

F_CubeSat_AerotechG80 is a variable.

Answer 1

[Mischa Kim]

It looks like your ODE function is called F__CubeSat_rocket:

 function ydot = F__CubeSat_rocket(t,y)

However, you are calling ode15s with F__CubeSat_AerotechG80

 [t y] = ode15s('F__CubeSat_AerotechG80',t,yo);

I assume you want

 [t y] = ode15s('F__CubeSat_rocket',t,yo);