How to find the best shift of experimental dataset from a model dataset.

Hello all,

I'm trying to fit one set of data (expt) to another dataset (from theory). The expt curve is shifted in x-direction by some value compared to the theory dataset. How can i fit these two curves and find the best shift parameter value (for expt data)? I'm trying to use lsqcurvefit function, but I cannot define my model as a function since I have (x,y) datapoints for model as well.

Thanks,

Chirag