Too Many Input Arguments Matlab ode45 - matlab

Question

I am trying to write a simple Matlab code to model a projectile. Whenever I try to run the code I get an error saying there are too many input arguments. I am running the code with
model1(44.7, 45)
function[] = model1(vel, angle)
close all;
tspan = [0 3];
x0 = [0; 0.915; vel*cos(angle); vel*sin(angle)];
[x] = ode45(#ball, tspan, x0);
function xdot = ball(x)
g = 9.81;
xdot = [x(3); x(4); 0; -g];
end
end
Error using model1/ball
Too many input arguments.
Error in odearguments (line 87)
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 model1 (line 9)
[x] = ode45(#ball, tspan, x0);
I'd appreciate any advice!

Answer 1

The error was (what I also committed many times in the past) that you have to pass the independent variable (time, in this case) too.
function [t, x] = model1(vel, angle)
tspan = [0 3];
x0 = [0; 0.915; vel*cos(angle); vel*sin(angle)];
[t, x] = ode45(#ball, tspan, x0);
end
function xdot = ball(t,x)
g = 9.81;
xdot = [x(3); x(4); 0; -g];
end
I modified your code to return the solution and the corresponding time steps. Moreover, I removed ball to be a nested function.