Undefined function or variable t

How do i solve the undefined variable t error, do i have to run it from another file ?

function dxdt=Math(t,x1) % function name
x=x1(1)
y=x1(2)
z=x1(3)
dxdt(1,1)= 22222222*z*z %define function
dxdt(2,1)=-0.06*y+11111*x*z
dxdt(3,1)=0.06*y-22222222*z*z-11111*x*z

x0=[0 1 0] % initial value of variable
tspan=[0:1:20] % time interval
[t_out,x_out]=ode45(@(t,x1) fun(t,x1),tspan,x0) % ode45 solver
plot(t_out,x_out(:,1)) %plot of function
xlabel('Time') % x axis name
ylabel('x') % y-axis name

plot(t_out,x_out(:,2)) %plot of function
xlabel('Time') % x axis name
ylabel('y') % y-axis name
plot(t_out,x_out(:,3)) %plot of function
xlabel('Time') % x axis name
ylabel('z') % y-axis name
end

Answer 1

[KSSV]

It looks like you are running the function striaght away by hitting the run button. No it cannot be done like that. The functions takes in two inputs, you have to define them and then call the function.

t = your array ;   % give your values of t 
x1 = your array ;  % give valus of x1 
dxdt=Math(t,x1) ;  % now call the function 

Answer 2

[James Tursa]

Put this code in a separate file called Math.m

% file Math.m
function dxdt=Math(t,x1) % function name
x=x1(1)
y=x1(2)
z=x1(3)
dxdt(1,1)= 22222222*z*z %define function
dxdt(2,1)=-0.06*y+11111*x*z
dxdt(3,1)=0.06*y-22222222*z*z-11111*x*z
end

Then pass a Math function handle to ode45:

[t_out,x_out]=ode45(@Math,tspan,x0) % ode45 solver