curve fit?

  		I am looking for a program (fortran or C) that will fit
 	a function (Morse like or n-order polynomial) to data (potential
         curve).  Does anyone know of any free programs available.  I
         checked the net and could not readily locate anything.  I will
 	summarize results.
 	Dan Lawson
 	lawson &$at$&
 	Graduate Student
 	Michigan State University