code: private void calcAxisFoldTypes() {
  		axisTypes = new int[multiplicity];
  
  		for (int i=0;i<this.transformations.size();i++){
  
  			axisTypes[i] = getRotAxisType(transformations.get(i));
  
  		}
  	}
docs: Calculates the axis fold type (1, 2, 3, 4, 5, 6 for rotations or -1, -2, -3, -4, -6 improper rotations)
  from the trace of the rotation matrix, see for instance
  http://www.crystallography.fr/mathcryst/pdf/Gargnano/Aroyo_Gargnano_1.pdf