Rational Spline only with breakpoints and knots

Hi I am trying to create a rational spline from the x,y points that I have. I am not really very experienced in splines.

Briefly; I have the X and the Y values and I want to create a rational spline and tweak the weights on the spline. But when I check the related functions in matlab, I need coefs,breaks or knots,coefs.

Is there another way to make this without coefs, or do I have to calculate the coefs? If so how can I make it from the x,y points that I have?

Excuse my lack of knowledge on splines- since it is not my area of expertise

Thanks in advance