code: public static void fractionalToCartesian(ICrystal crystal) {
          Iterator<IAtom> atoms = crystal.atoms().iterator();
          Vector3d aAxis = crystal.getA();
          Vector3d bAxis = crystal.getB();
          Vector3d cAxis = crystal.getC();
          while (atoms.hasNext()) {
              IAtom atom = atoms.next();
              Point3d fracPoint = atom.getFractionalPoint3d();
              if (fracPoint != null) {
                  atom.setPoint3d(fractionalToCartesian(aAxis, bAxis, cAxis, fracPoint));
              }
          }
      }
docs: Creates Cartesian coordinates for all Atoms in the Crystal.