/** {@inheritDoc} */
 public FieldVector<T> mapInvToSelf() {
   final T one = field.getOne();
   for (int i = 0; i < data.length; i++) {
     data[i] = one.divide(data[i]);
   }
   return this;
 }
 /** {@inheritDoc} */
 public FieldVector<T> mapInv() {
   T[] out = buildArray(data.length);
   final T one = field.getOne();
   for (int i = 0; i < data.length; i++) {
     out[i] = one.divide(data[i]);
   }
   return new ArrayFieldVector<T>(field, out, false);
 }