iFit/sw_res

 reads a tabulated energy resolution from a file and fits with polynomial

 p = SW_RES(fid,polDeg,{plot})

 The file contains the FWHM energy resolution values as a function of
 energy transfer in two columns, first the energy transfer values
 (positive is energy loss), the second is the FWHM of the Gaussian
 resolution at the given energy transfer value.

 Options:

 fid           String, path to the resolution file or a matrix with the
               same format as the data file.
 polDeg        Degree of the fitted polynomial to the instrumental
               resolution data. Default is 5.
 plot          If true the resolution will be plotted, optional, default
               is true.

 Output:

 p             Returns the coefficients for a polynomial p(x) of degree n
               that is a best fit (in a least-squares sense) for the resolution data
               in y. The coefficients in p are in descending powers, and
               the length of p is n+1.
               p(x)=p_1*x^n+p_2*x^(n-1)+...+p_n*x+p_(n+1).

 See also POLYFIT, SW_INSTRUMENT.