correct8Term

      correct8Term    returns DUT S parameters from 8-term error model
         Scorr = correct8Term(Sm,A,B,q)
         input:
             Sm: [2,2,num_pts] raw measured DUT S-parmeters
             A,B,q: 8-term mdoel error terms from get8TermModel()
         output:
             S: [2,2,num_pts] corrected DUT S-params