code: public AxisAngle4d set(AxisAngle4d a) {
          x = a.x;
          y = a.y;
          z = a.z;
          angle = (a.angle < 0.0 ? Math.PI + Math.PI + a.angle % (Math.PI + Math.PI) : a.angle) % (Math.PI + Math.PI);
          return this;
      }
docs: Set this {@link AxisAngle4d} to the values of <code>a</code>.
  
  @param a
  the AngleAxis4f to copy the values from
  @return this