public RotationMatrixBuilder withThetas(double theta){
  for (  Plane plane : planes) {
    plane.setTheta(theta);
  }
  return this;
}

public RotationMatrixBuilder withThetas ( double theta ) { for ( Plane plane : planes ) { plane . setTheta ( theta ) ; } return this ; }
sets the rotation angle , in radians , of all 2d rotation planes added to this builder .
