custom equation fit with weighted LS fit

Hey everybody.. m new to MATLAB..

I have a file with x,y coordinates and error with y.

I want to do least square fitting of an equation y(x) = a*(x^(-1/b)-37^(-1/b))

Please help me.

I tried with cftool... but the values of a and b are coming double the desired values...what could b the reason...?? and how to rectify it??

can we do without cftool?? does x range and y range also effect the fit parameters values?? if yes how to give range ??

its been days m stuck in this... plz help me.. i wl b highly obliged ... thanks