MATLAB: Not enough input arguments ode45

Question

Hi everyone,

I have a problem with an ode45 function. Hier is my code:

function dx=num_lsg1(t,x) 
  dx=zeros(2,1);
  dx(1)=k*x(2)-x(1)*(1-x(2));
  dx(2) = (x(1)*(1-x(2))-kmm*x(2))/e;
%def parameters
k=0.625;
e=0.001;
kmm=1;
s0=1;
c0=0;
t=linspace(0,0.01,100);
x0=[s0 c0];
% Main program
[t,x]=ode45(@(t,x) num_lsg1(t,x), t, x0);
plot(x(:,1),'-o', x(:,2),'-x');
end

Hier is the arror message:

>> num_lsg1

Not enough input arguments.

Error in num_lsg1 (line 5)

dx(1)=k*x(2)-x(1)*(1-x(2));

Could someone help me to find the problem?

Thank you!

Answer 1

% Main program

s0=1;
c0=0;
t=linspace(0,0.01,100);
x0=[s0 c0];
% Main program
[t,x]=ode45(@(t,x) num_lsg1(t,x), t, x0);   % function call
plot(t,x(:,1),'-o')
figure              % plot it in separate figure because obviously the scales are different
plot(t, x(:,2),'-x');
function dx=num_lsg1(t,x)  % function definition
%def parameters  
k=0.625;      % have t be defined before usage (that's why you had error)
e=0.001;
kmm=1;
  dx=zeros(2,1);
  dx(1)=k*x(2)-x(1)*(1-x(2));
  dx(2) = (x(1)*(1-x(2))-kmm*x(2))/e;
end