curve fitting in the frequency domain

hi,

i am looking to get some frequency response data, in the form of a bode plot. When i obtain this data, i would like to plot the results in matlab, and then obtain a transfer function that describes the characteristics of the data. So, i am wondering if anyone knows of some simple tools that are built into matlab that is able to do curve fitting based on a entered bode plot.

i.e. given a bode plot, matlab returns a transfer function of the frequency response.

tia