I've a possibility to calculate a numerical solution for the differential equation:

I create a function called deqex:

function dydx=deqex(x,y)

dydx = 1/(2*x^2*y-1)

in the main programm, I solved the equation with:

[x,y]=ode23('deqex',[0,100],1.856*exp(-1i*pi/3));

Now I have the problem that I don't know how to calculate the derivations of the solution at the point x=0

Can anybody help?