Why do I get the error (not enough input arguments) when run the script about 2nd-order Adams-Bashforth (Explicit Method)?

Greetings!

Can someone help me review my code about solve ODE-IVPs using 2nd-order Adams-Bashforth (Explicit Method)? Because I faced error (Not enough input arguments) when I run the script.

Thanks in advance

function [t,y] = AB2(fun,tspan,y0,y1,y2,N)
a = tspan(1);
b = tspan(2);
h = (b-a)/N;
t = zeros(N+1,1);
y = zeros(N+1,1);
t(1) = a; y(1) = y0;
t(2) = a+h; y(2) = y1;
for i = 2:N
    t(i+1) = t(i) + h;
    Fi = fun(t(i),y(i));
    Fi1 = fun(t(i-1),y(i-1));
    y(i+1) = y(i) + h/2*(3*Fi - Fi1);
end

%% 2nd-order Adams-Bashforh Solution
fun = @(t,y) ((1+4*t)*((y)^1/2)); %Function f(t,y)
y0 = 1; %Initial Condition
tspan = [0,1];
N = 4; %Number of subintervals, h = (b-a)/N
%% Initial Values
h = (tspan(2) - tspan(1))/N;
exactY = @(t) @(t) (((3*t)/2)+3*t.^2).^(2/3);
t1 = tspan(1) + h; y1 = exactY(t1);
t2 = tspan(1) + 2*h; y2 = exactY(t2);
[t2,Y2] = AB2(fun,tspan,y0,y1,N);
%% Display Solution
Y = exactY(t2);
disp('-----------------------------'); 
disp('t_i   y(t_i)   AB2   Error')
disp('-----------------------------'); 
formatSpec = '%.2f   %.5f   %.5f   %.5f\n';
fprintf(formatSpec,[t2';Y';Y2';abs(Y'-Y2')])

Answer 1

[Walter Roberson]

%%2nd-order Adams-Bashforh Solution

move everything from that line onwards to a new file, and execute that other file.

[Yusuf Arya Yudanto]

It still error. When I moved the everything on

%%2nd-order Adams-Bashforh Solution

to a new file, and execute that other file. It showed

Unrecognized function or variable 'tspan'.

Error in HW2Number1AB2OK (line 7)
h = (tspan(2) - tspan(1))/N;

[Torsten]

function [t,y] = AB2(fun,tspan,y0,y1,y2,N)

[t2,Y2] = AB2(fun,tspan,y0,y1,N);

Do you see that the function needs one more input parameter than you supply in the call ?

[Yusuf Arya Yudanto]

Yes, I just realized it. It worked already. Thanks!