code: public double getRelativeAsaU() {
  		if (!g.getType().equals(GroupType.AMINOACID))
  			throw new IllegalArgumentException("Can not calculate relative ASA for non amino-acid");
  
  		char aa = ((AminoAcid)g).getAminoType();
  
  		return (asaU/tripeptAsa.get(aa));
  
  	}
docs: Returns the relative (uncomplexed) ASA, i.e. the ASA of the residue
  with respect to its ASA in an extended tri-peptide conformation (GLY-x-GLY)
  @return