How to solve for dI/dz differential equation using runge kutta 4th order method?

[James Tursa]

You have multiple independent variables listed, t and z. I think we need more information about what your overall problem is and what initial or boundary conditions you have.

Answer 1

[Sudharsana Iyengar]

use ode45

create a function of your diffrential equations and use ODE 45.

This is an example, do a similar for yours.

function dydt = odefcn(t,y,A,B)
  dydt = zeros(2,1);
  dydt(1) = y(2);
  dydt(2) = (A/B)*t.*y(1);
end

Then call your function

A = 1;
B = 2;
tspan = [0 5];
y0 = [0 0.01];
[t,y] = ode45(@(t,y) odefcn(t,y,A,B), tspan, y0);

plotting result

plot(t,y(:,1),'-o',t,y(:,2),'-.')