Find the inflection point of a discrete dataset in Matlab

Question

I have a dataset (an array with x and y values) to which I eventually want to fit a nonlinear model. In order to increase the chances that the fit will be good and that the model will converge, I want to supply initial parameters as close to the solution as possible. One of the parameter of the model I want to fit corresponds to the inflection point of the curve. Is there a way I can estimate the inflection point of a discrete dataset (not a continuous function) in Matlab? I don't want to have to curvefit beforehand since this is intended to accelerate the curvefit and increase its probability of being successful.