Not enough input arguments.

Why do I get an error when create the M-File "Lorenz" with the following input:

function xprime = Lorenz(t,x);
%LORENZ: Computes the derivatives involved in solving the Lorenz equations
sig = 10;
beta = 8/3;
rho=28;
xprime=[-sig*x(1) + sig*x(2);rho*x(1)-x(2)-x(1)*x(3);-beta*x(3) +x(1)*x(2)];

The error says:

Error in Lorenz (line 6)

xprime=[-sig*x(1) + sig*x(2);rho*x(1)-x(2)-x(1)*x(3);-beta*x(3) +x(1)*x(2)];

[per isakson]

I get the error (R2018b)

Error using vertcat
Dimensions of arrays being concatenated are not consistent.
Error in Untitled2>Lorenz (line 11)
    xprime=[-sig*x(1) + sig*x(2); rho*x(1)-x(2)-x(1)*x(3); -beta*x(3) +x(1)*x(2)];
Error in Untitled2 (line 4)
xprime = Lorenz( t, x ); 

I cannot see that this statement (Lorenz (line 6)) could throw the error "Not enough input arguments."

Show your full error message.

Answer 1

[per isakson]

You need to call the function, Lorenz, with two input arguments: t and x. E.g.

%%
x = (1:6);
t = nan;
xprime = Lorenz( t, x )

In your case the variable, x, is not defined in the workspace of Lorenz. Thus, the expression cannot be evaluated. Don't ask me why the error message isn't more informative.