


 EVOKED_POTENTIAL estimates evoked potentials (EP's)
  R = EVOKED_POTENTIAL(filename, CHAN, t_start, t_end,EventTyp)
  R = EVOKED_POTENTIAL(s, HDR, t_start, t_end,EventTyp)
     filename  filename
     CHAN      channel selection; default: 0 (all)
     t_start   start time in seconds (relative to trigger time point)
     t_end     end time in seconds relative to trigger 
     EventTyp  [optional]
  The trigger information must be available in the biosig file. 
  The EP is calculated for each selected channel, if classlabels 
  are available, the EP is calculated for each class