Problem using ode45

I have two files: 1 file has this code: function xprime = lorenz(t,x); alfa = 0.017; beta = 0.067; tau_e = 0.017; tau_l = 0.0001; tau_j =0.00000001; tau_k =0.00000001; c = 0.000001; p = 0.000001; d = 0.000001; A = 475; xprime = zeros(6,1); t0=20.0; xprime(1) =A*( c1*x(2) + x(3)*tau_k -(tau_l*x(1) - tau_j*x(1))); and so on

second file has this code clear all; x0 = [0 0 0.8 0.2 0 0]; tspan = [0 500]; [t,x]=ode45(@lorenz,tspan,x0); save('A475.mat','x','t')

Because I want to calculate a lot of ode but each with different A - how can i put A value in my second file ?

I was trying like clear all; x0 = [0 0 0.8 0.2 0 0]; tspan = [0 500]; A=475; [t,x]=ode45(@lorenz,tspan,x0,[],A); save('A475.mat','x','t')

but it gives me an error. Undefined function or variable 'A'.

Error in lorenz (line 107) xprime(1) =A*( c1*x(2) + x(3)*tau_k -(tau_l*x(1) - tau_j*x(1)));

Error in odearguments (line 90) 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 run (line 5) [t,x]=ode45(@lorenz,tspan,x0,A);

I'm using matlab version R2017a

Answer 1

[Star Strider]

Include ‘A’ in the argument list to ‘lorenz’, then pass it as an extra parameter in your ode45 call.

Function:

function xprime = lorenz(t,x,A);
  ...
end

Calling script:

...
A = 475;
[t,x] = ode45(@(t,x)lorenz(t,x,A) ,tspan,x0);

See the documentation on Passing Extra Parameters (link) for a detailed description.