How to write code for finding curvature of an ellipse using centered difference method?

I have an ellipse with equation (x/a)^2+(y/b)^2=1. where a=1 and b=2.we can calculate Y values for different x values.In the attachment i have taken step size as 0.4.But i have to change the values as h=0.1:0.1:1.And need to calculate the first and second derivative using the centered difference method and thereby calculate the curvature and plot it with X values