question: public RealMatrix create ( ) { RealMatrix rotation = newIdentityMatrix ( ) ; for ( Plane plane : planes ) { double theta = plane . getTheta ( ) ; if ( Double . isNaN ( theta ) ) { continue ; } rotation = rotation . multiply ( newRotationMatrix ( plane . getFirstAxis ( ) , plane . getSecondAxis ( ) , theta ) ) ; } return rotation ; }
target:  Returns the rotation matrix resulting from applying all 2D rotation  planes and angles added to this builder.