How can I fix this program with ODE45?

Code:

clc, close all;

hours = 3600;

days = 24*hours;

deg = pi/180;

mu = 398600;

RE = 6378;

wE = [ 0 0 7.2921159e-5]';

CD = 2.2;

m = 100;

A = pi/4*(1^2);

rp = RE + 215;

ra = RE + 939;

RA = 339.94*deg;

i = 65.1*deg;

w = 58*deg;

TA = 332*deg;

e = (ra-rp)/(ra+rp);

a = (rp + ra)/2;

h = sqrt(mu*a*(1-e^2));

T = 2*pi/sqrt(mu)*a^1.5;

coe0 = [h e RA i w TA];

[R0, V0] = sv_from_coe(coe0, mu);

r0 = norm(R0);

v0 = norm(V0);

t0 = 0;

tf = 120*days;

y0 = [R0 V0]';

nout = 40000;

tspan = linspace(t0, tf, nout);

% Set error tolerances, initial step size, and termination event:

options = odeset(’reltol’, 1.e-8, ...

’abstol’, 1.e-8, ...

’initialstep’, T/10000, ...

’events’, @terminate);

global alt %Altitude

[t,y] = ode45(@rates, tspan, y0,options); %t is the solution times

Result:

Please, help me to answer my last project with this method. I'm still confusing about this problem. Anything idea?

Answer 1

[Ameer Hamza]

You are using the wrong character (’) in your code. MATLAB does not recognize it to create strings. Use the apostrophe symbol (') instead. For example, copy and paste the lines in your code and delete the older lines

options = odeset('reltol', 1.e-8, ...
'abstol', 1.e-8, ...
'initialstep', T/10000, ...
'events', @terminate);