ode45 errorI have

I have the following code:

%% 22.initial input data vector

IDATA=[X0 Y0 Z0 Vx0 Vy0 Vz0];

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%% %%%%%%%%%%%%% END OF INITIAL INPUTS AND CALCULATIONS %%%%%%%%%%%%%%%%%%%

%% ODE

Tol = 1e-12;

Tol0 = 1e-9;

tspan = (1:TS:TT0);

options = odeset('RelTol', Tol, 'AbsTol', Tol0);

% Assuming IDATA contains the initial conditions for your system

IDATA = [X0,Y0,Z0,Vx0,Vy0,Vz0];

[t, y] = ode45(@ODAYRK1, tspan, IDATA, options);

X = y(:,1);

Y = y(:,2);

Z = y(:,3);

Vx = y(:,4);

Vy = y(:,5);

Vz = y(:,6);

and the following ode45 function:

function ODAYRK = ODAYRK1(t, y)

global M e0 mi r0

% Extracting variables from the state vector

X = y(1);

Y = y(2);

Z = y(3);

Vx = y(4);

Vy = y(5);

Vz = y(6);

% Compute some intermediate values

r = sqrt(X.^2+ Y.^2+Z.^2);

% Define the ODEs

dXdt = Vx;

dYdt = Vy;

dZdt = Vz;

dVxdt = mi/r.^3.*X;

dVydt = mi/r^.3.*Y;

dVzdt = mi/r.^3.*Z;

% Assemble the derivative vector

ODAYRK = [dXdt;dYdt;dZdt;dVxdt;dVydt;dVzdt];

ends

and the following error:

Error in ode45 (line 115)

odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Error in test1971 (line 97)

[t, y] = ode45(@ODAYRK1, tspan, IDATA, options);

please help

Answer 1

[Sam Chak]

Some corrections in the ODE function (ODAYRK1)

Tol     = 1e-12;
Tol0    = 1e-9;
tspan   = [0 10];
options = odeset('RelTol', Tol, 'AbsTol', Tol0);
% Assuming IDATA contains the initial conditions for your system

IDATA  = [1, 0, 0, 0, 0, 0];
[t, y] = ode45(@ODAYRK1, tspan, IDATA, options);
plot(t, y), grid on

function ODAYRK = ODAYRK1(t, y)
    % global M e0 mi r0
    
    mi = 1;     % <-- define it inside the ode function
    
    % Extracting variables from the state vector
    X  = y(1);
    Y  = y(2);
    Z  = y(3);
    Vx = y(4);
    Vy = y(5);
    Vz = y(6);
    % Compute some intermediate values
    r = sqrt(X^2 + Y^2 + Z^2);
    
    % Define the ODEs
    dXdt  = Vx;
    dYdt  = Vy;
    dZdt  = Vz;
    dVxdt = mi/(r^3)*X;
    dVydt = mi/(r^3)*Y;     % <-- correction at this line
    dVzdt = mi/(r^3)*Z;
    
    % Assemble the derivative vector
    ODAYRK = [dXdt; dYdt; dZdt; dVxdt; dVydt; dVzdt];
end