docs: @Pure
  	public ReadOnlyUnitVectorProperty secondAxisProperty() {
  		if (this.saxis == null) {
  			this.saxis = new ReadOnlyUnitVectorWrapper(this, MathFXAttributeNames.SECOND_AXIS, getGeomFactory());
  			this.saxis.bind(Bindings.createObjectBinding(() -> {
  				final Vector2dfx firstAxis = firstAxisProperty().get();
  				return firstAxis.toOrthogonalVector();
  			},
  					firstAxisProperty()));
  		}
  		return this.saxis.getReadOnlyProperty();
  	}