text: // This file is part of libigl, a simple c++ geometry processing library.
  // 
  // Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
  // 
  // This Source Code Form is subject to the terms of the Mozilla Public License 
  // v. 2.0. If a copy of the MPL was not distributed with this file, You can 
  // obtain one at http://mozilla.org/MPL/2.0/.
  #ifndef IGL_ANGULAR_DISTANCE_H
  #define IGL_ANGULAR_DISTANCE_H
  #include "igl_inline.h"
  #include <Eigen/Geometry>
  namespace igl
  {
    // The "angular distance" between two unit quaternions is the angle of the
    // smallest rotation (treated as an Axis and Angle) that takes A to B.
    //
    // Inputs:
    //   A  unit quaternion
    //   B  unit quaternion
    // Returns angular distance
    IGL_INLINE double angular_distance(
      const Eigen::Quaterniond & A,
      const Eigen::Quaterniond & B);
  }
  
  #ifndef IGL_STATIC_LIBRARY
  #include "angular_distance.cpp"
  #endif
  
  #endif
  