public void set(int offset, double[] values) {
   synchronized (mutex) {
     list.set(offset, values);
   }
 }
 public void set(int offset, double[] values, int valOffset, int length) {
   synchronized (mutex) {
     list.set(offset, values, valOffset, length);
   }
 }
 public double set(int index, double element) {
   synchronized (mutex) {
     return list.set(index, element);
   }
 }