I've been getting several errors, especially "index must be a positive integer or logical."

    Hello, I've been trying to run this code and it keeps getting the following errors:

    Attempted to access k2(0); index must be a positive integer or logical.

    Error in toluene (line 14)
    r(3)= -k1*P(1)*(P(2)^0.5)+(2*k2(P(3)^2-(P(5)*P(2)/Kp)));

    Error in odearguments (line 87)
    f0 = feval(ode,t0,y0,args{:});   % ODE15I sets args{1} to yp0.

    Error in ode45 (line 113)
    [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

    Error in Untitled2 (line 12)
    [V,F]= ode45('toluene', Vspan, F0);

    I don't really know what's wrong?
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This is the code:

    function dFdV = toluene(~, F) 
    global k1 k2 Kp Pt0

    Ft = F(1)+F(2)+F(3)+F(4)+F(5);

    P(1)= Pt0*(F(1)/Ft);
    P(2)= Pt0*(F(2)/Ft);
    P(3)= Pt0*(F(3)/Ft);
    P(4)= Pt0*(F(4)/Ft);
    P(5)= Pt0*(F(5)/Ft);

      r(1)= -k1*P(1)*(P(2)^0.5);
      r(2)= -k1*P(1)*(P(2)^0.5)+(k2*(P(3)^2-(P(5)*P(2)/Kp)));
      r(3)= -k1*P(1)*(P(2)^0.5)+(2*k2(P(3)^2-(P(5)*P(2)/Kp)));
      r(4)= k1*P(1)*(P(2)^0.5);
      r(5)= k2*((P(3)^2)-((P(5)*P(2))/Kp));

      dFdV= [r(1); r(2); r(3); r(4); r(5)];

      end

   clear;

    global k1 k2 Kp Pt0;
    k1= 2.22*10^-8;
    k2= 3.60*10^-10;
    Kp= 0.2338;
    Pt0= 600;

    Vspan= [0 608];
    F0= [0.121   2.42  0  0  0];

    [V,F]= ode45('toluene', Vspan, F0);

Answer 1

[James Tursa]

In one line you have this:

...+(k2*(...

and in the next line you have this:

...+(2*k2(...

I assume the 2nd line is a typo and is missing a multiply operator:

...+(2*k2*(...

[Franchesca Rivera]

Thank you! It doesn't show an error anymore! It worked!